Is there any lesson about indirect speech(le discours indirect), because I can't find any grammar lesson about it.

Hi Niloofar,

It is in the pipeline....

If you take a look at the following question posted last January , there is a summary on indirect speech posted by me which hopefully will enlighten you in the meantime -

https://progress.lawlessfrench.com/questions/view/imperfect-and-passe-compose-in-mamie-gateau-lesson