One of the most used keyboard shortcut is F2, which allows to edit the formula in a cell without using the mouse. Unfortunately that shortcut is different between Office for Mac and Office Windows.
This shortcut was F2 in a PC, but in Excel for Mac it turns into Ctrl + U. Unfortunately not the most effective shortcut, as it's rather difficult to press Ctrl + U with one hand on most keyboards.
Windows Shortcut: F2
Mac Shortcut: Ctrl + U