Use of error handlers with SpecialCells: Using SpecialCells in VBA can potentially throw errors, particularly Error 1004 when no cells of the specified type are found. It's good practice to have error handling in place for these instances. An example implementation might look like this:

On Error Resume Next Set rngSpecial = Table.SpecialCells(xlCellTypeVisible) If Err.Number <> 0 Then Err.Clear ' Handle error or exit function End If On Error GoTo 0

Storing the result of SpecialCells in a variable: The SpecialCells method is called multiple times in this code. This method can be resource intensive, particularly with larger ranges. Storing the result in a variable and then using that variable would improve efficiency. Example:

Dim rngSpecial As Range Set rngSpecial = Table.SpecialCells(xlCellTypeVisible) Now, you can use rngSpecial instead of calling Table.SpecialCells(xlCellTypeVisible) each time.

Misleading variable name - Trimdata: The variable name Trimdata can be misleading because in programming contexts, "trim" is often used to refer to removing white spaces from the start and/or end of strings. Here, a more accurate name might be FilteredData or VisibleData to better reflect that this array contains only the visible (i.e., unfiltered) data from the range.

Simpler calculation of row numbers: The calculation for the number of rows in a range can be simplified by dividing the total count of cells in the range by the count of columns. This can be done as follows:

numRows = Table.Count / Table.Columns.Count

Remember that this will give you the total number of rows, including those hidden by filters. If you only want the number of visible rows, you would need to perform this operation on the range returned by SpecialCells(xlCellTypeVisible).

' This function accepts a range in Excel (the "Table") as input and returns a filtered array that excludes any hidden or non-visible cells in the range.
Function ArrayFromFilteredRange(Table As Range) As Variant
    ' Declare a Range object to hold the target cells
    Dim Target As Range
    ' In case of any error in the following operations, program execution will resume at the next statement
    On Error Resume Next
    ' Assign to "Target" only the visible cells from "Table"
    Set Target = Table.SpecialCells(xlCellTypeVisible)
    ' Resets the error handling to its default behavior
    On Error GoTo 0
    ' If no visible cells were found, return an empty array and exit the function
    If Target Is Nothing Then
        ArrayFromFilteredRange = Array()
        Debug.Print "ArrayFromFilteredRange:", "Target Is Nothing"
        Exit Function
    End If

    ' Declare a variable to hold the number of columns in the target range
    Dim columnCount As Long
    columnCount = Target.Columns.Count

    ' Declare a variable to hold the number of rows in the target range
    Dim rowCount As Long
    rowCount = Target.Count / columnCount
 
    ' Declare an array to hold the data from the target range
    Dim Result As Variant
    ' Set the dimensions of the Result array to match the size of the target range
    ReDim Result(1 To rowCount, 1 To columnCount)

    ' Declare variables to assist in navigating the target range and populating the Result array
    Dim Area As Range
    Dim AreaData As Variant
    Dim c As Long, r As Long, row As Long

    ' Loop through each area of the target range
    For Each Area In Target.Areas
        ' Loop through each row in the current area
        For row = 1 To Area.Rows.Count
            ' Increment the row count for the Result array
            r = r + 1
            ' Extract the values from the current area
            AreaData = Area.Value
            ' Loop through each column in the current area
            For c = 1 To columnCount
                ' Assign the current cell's value to the corresponding element in the Result array
                Result(r, c) = AreaData(row, c)
            Next
        Next
    Next

    ' Return the Result array
    ArrayFromFilteredRange = Result
End Function

Addendum

I overlooked the whole point of the OP's code. He postulates that it is more efficient to load all the data into a variable and loop over it. As opposed to iterating over each areas values.

' This function calculates the relative row index of an area within a given target range.
' It takes the target range and area index as inputs and returns the relative row index.
Function GetAreaRelativeRowIndex(Target As Range, AreaIndex As Long) As Long

    ' Get the row number of the first cell in the given area within the target range
    ' Subtract the row number of the first cell in the target range to calculate the relative row index
    ' Adding 1 at the end accounts for the 1-based index system in VBA
    GetAreaRelativeRowIndex = Target.Areas(AreaIndex).Row - Target.Row + 1

End Function
' This function accepts a range in Excel (the "Table") as input and returns a filtered array
' that excludes any hidden or non-visible cells in the range.
Function FilteredRangeData(Table As Range) As Variant

    ' Declare a Range object to hold the target cells
    Dim Target As Range
    
    ' On Error Resume Next allows the program to continue with the next line of code 
    ' even if there is an error
    On Error Resume Next
    
    ' Assign to "Target" only the visible cells from "Table"
    ' .SpecialCells(xlCellTypeVisible) allows to target only cells that are visible
    Set Target = Table.SpecialCells(xlCellTypeVisible)
    
    ' Resets the error handling to its default behavior
    On Error GoTo 0

    ' If no visible cells were found or if Table is a single cell, 
    ' return an empty array and exit the function
    If Target Is Nothing Or Table.Count = 1 Then
        Dim EmtpyResult(1 To 1, 1 To 1) ' Define a 1x1 array
        FilteredRangeData = EmtpyResult ' Set function result as the empty array
        Debug.Print "FilteredRangeData:", "Target Is Nothing" ' Output message for debugging
        Exit Function ' Exit the function
    End If

    ' Declare a variable to hold the number of columns in the target range
    Dim columnCount As Long
    columnCount = Target.Columns.Count

    ' Declare a variable to hold the number of rows in the target range
    ' This is calculated by dividing the total count of cells in the target by the column count
    Dim rowCount As Long
    rowCount = Target.Count / columnCount
 
    ' Declare an array to hold the data from the target range
    Dim Result As Variant
    ' Set the dimensions of the Result array to match the size of the target range
    ReDim Result(1 To rowCount, 1 To columnCount)
    
    ' Declare a variable to store all values in the table
    Dim AllValues As Variant
    AllValues = Table.Value
    
    Dim AreaIndex As Long
    Dim AreaRowCount As Long
    Dim AreaRelativeRowIndex As Long
    Dim Count As Long
    Dim r As Long
    Dim c As Long
    
    ' Loop through all the areas in the target range
    For AreaIndex = 1 To Target.Areas.Count
        ' Get the relative row index of the current area in the target range
        AreaRelativeRowIndex = GetAreaRelativeRowIndex(Target, AreaIndex)
        ' Get the number of rows in the current area
        AreaRowCount = Target.Areas(AreaIndex).Rows.Count
        ' Loop through all the rows in the current area
        For r = AreaRelativeRowIndex To AreaRelativeRowIndex + AreaRowCount - 1
            ' Increment the count
            Count = Count + 1
            ' Loop through all the columns
            For c = 1 To columnCount
                ' Assign the cell value in AllValues to the corresponding cell in Result
                Result(Count, c) = AllValues(r, c)
            Next c
        Next r
    Next AreaIndex
    
    ' Return the Result array
    FilteredRangeData = Result
End Function