Select All ("cmd" + "a" shortcut) to select all of the text in a cell…
Can't believe this doesn't exist! Come on MS.
Jack C commented
Selects the entire worksheet.
If the worksheet contains data, CTRL+A selects the current region. Pressing CTRL+A a second time selects the current region and its summary rows. Pressing CTRL+A a third time selects the entire worksheet.
When the insertion point is to the right of a function name in a formula, displays the Function Arguments dialog box.
CTRL+SHIFT+A inserts the argument names and parentheses when the insertion point is to the right of a function name in a formula.