To do Alt + H H on Mac in Excel, download and install Accelerator Keys, then press Option, followed by H and H.
Command: Fill Color (Cell Shading)
This is how to do Alt + H H 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 H opens the Fill Color (cell shading) dropdown menu in the Font group on the Home tab. This allows you to quickly apply a background color to selected cells to highlight important data, create visual groupings, or improve spreadsheet readability. Click a color to apply it, or use the menu to access more color options.