Here are all the tutorials about SFML from the basic one to the advanced. I will try to add ore tutorial on SFML on advanced topic. You can also find some tutorials on the official website. You can find some example of games made with SFML on wikipedia.
If you are beginning in game development this section is where you should start 🙂.
The tutorials are small and very easy to follow you can download the full project on itch.io
After you have some experience you will need to make tools for your game, create maps, collisions or use shaders, here is a section where you can find more advanced example built with SFML.