Should I put any word or abbreviation next to my deceased spouse's name, died July 2020, for this last joint return?

You will mark that your spouse is deceased and the date that your spouse passed.

You do not add anything to your deceased spouse's name. In the My Info section of TurboTax, after you enter your spouse's name and other information, the next screen has a box to check to indicate that your spouse passed away. Check that box and enter the date of death. TurboTax will then make the necessary notation on your tax return.