I was doing up several worksheets in Excel, and I was finding it incredibly disruptive to my workflow to edit a cell. I had to take my hands off my keyboard, reach out to my mouse, and double-click the cell before I could edit it. So I went searching, and turns out that there’s a keyboard shortcut for this! Just press Ctrl-U to edit the cell contents! Not sure why they chose the letter u though.
How To Edit Cell With A Keyboard Shortcut In Mac Excel