If you just undo the previous action, click Undo on the Quick Access Toolbar (or press CTRL + Z), and if you want to undo the multi-step operation, click Continuously.
If you want to redo the action that was undone, click Restore (or press CTRL + Y).
Tip: When you open or close a file, you will not be allowed to undo all previous actions.
This can help you fix what you want when you edit the document if there is an error. Like an eraser, or a beauty tool, you'll do your best in any case!