Who is asking for that? If you used TurboTax to prepare a tax return, you would not have a form 8879, because your return was "self-prepared". TurboTax provides "do-it-yourself" tax software. That form 8879 is only used by paid professional tax preparers.
See this other post on the same issue:
https://ttlc.intuit.com/community/after-you-file/discussion/i-need-my-form-8879-how-do-i-get-this/00...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**