Here is an informal list of sources where you will find French content:
A "peer reviewed" article (also called a "scholarly" or "academic" journal article) is an article that has been reviewed by other scholars (peers) working in the same field.
Not all journal articles are peer reviewed. Many databases allow you to limit your search to peer-reviewed articles.
The database Ulrich's Periodical Directory can be used to check if a journal is peer-reviewed. Type the journal name into the search box. Click on the title in the list of results. If the category Refereed - Yes appears, it is a peer-reviewed journal.
Letters to the editor, comments and editorials are not peer-reviewed.