I never done a foreign tax return, but I want to learn.

A client moved to France in 2019. In 2020 she worked as a teacher in a University earning 18,313.80 Euros & 10,328 self employment doing tours. No W-2, She filed a return to French Gov. She's a US citizen. I tried reading and understanding all the articles but still not clear. I figure I might get a better understanding with posting her specific facts and hope someone can guide me. Is it in form 1116?  or 2555?

I appreciate your help