Got a letter from IRS again. Second one. First one dated March 6,2020. Second one dated July 24,2020. I don't understand

This is a user to user forum. You can probably get help from this forum by providing more detail on what the IRS notice says. 

If you purchased Audit Defense for your tax return, call Tax Resources, Inc. at 877-829-9695, or report your notice on their web site at http://intuit.taxaudit.com/. Do not contact the IRS. Let Tax Resources contact them for you.

If you did not purchase Audit Defense, you can try downloading and running the Audit Support Center at the following link.

https://turbotax.intuit.com/best-tax-software/why-choose-turbotax/audit-support.jsp

 (scroll down for more options)

See this TurboTax support FAQ for a list of Letters and Notices from the IRS - https://ttlc.intuit.com/questions/3605673-i-got-a-letter-or-notice-from-the-irs

One important rule of thumb: don't ignore the first IRS letter. 

All IRS letters have a form number that starts with"LTR" or "CP" followed by anywhere from 2 to 6 digits. So what form letter did you received? Also take note there is a "drop dead" date on that letter. If you don't respond to that letter by that date, you lose with no possible recourse.