To do Alt + H O U L on Mac in Excel, download and install Accelerator Keys, then press Option, followed by H, O, U, and L.
Command: Unhide Columns
This is how to do Alt + H O U L on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + H O U L unhides hidden columns within the selected range. Select the columns surrounding the hidden columns first, then use this shortcut to reveal the hidden data.