There are typically 3 feeds:
- Subscribed - this only shows posts from communities you have subscribed
- Local - only posts from communities on your local or home instance, you may see post's and comments from people on other instances, but all of the communities are on sh.itjust.works
- All - this shows all posts from communities across any instance*
- only posts from communities that a user on your home instance is subscribed to appear, also your instance can block instances. Those blocked instances will not appear.
Re French: there is an instance called jlai.lu that is a French instance. You can check out their communities and subscribe for more French content.