Hide and Unhide Columns Dialog Box
The Hide and Unhide Columns dialog box provides a convenient way to hide and unhide columns in the PowerPivot window. To access this dialog box, on the Design tab, in the Columns group, click Hide and Unhide.
You might hide columns if you want to work with a subset of the data in the PowerPivot window, but you might need to unhide them as you shift the focus of your analysis. For example, suppose your workbook contains many tables with hidden columns. Rather than going through each table individually to unhide columns, you can click Select all, and then check the box in the In PowerPivot and In Pivot columns to make all columns visible everywhere. For more information, see Freeze Columns.
This feature is not intended to be used for data security--only to simplify and shorten the list of columns in the PivotTable field list and PowerPivot window.