property Columns.Item (Index as Variant) as Column
Returns a specific Column giving its index/caption.

Index as Variant A Long expression that specifies the index of the column to be requested, a String expression that indicates the caption of the column to be accessed.
Column A Column object being requested.
The Item property gets the Column object based on its index or caption. The Count property specifies the number of data columns. The ClearData method clears the control's data. The PivotColumnsFloatBarVisible property specifies whether the Columns collection is displayed to a floating bar, so user can drag and drop columns to the control's pivot bar so it gets data summarized. You can use the for each statement to enumerate the data columns in the control.

The following VB sample enumerates the data columns:

With Pivot1
    Dim c As EXPIVOTLibCtl.Column
    For Each c In .DataColumns
        Debug.Print c.Caption
End With