Flarum is an application developed with PHP infrastructure and mostly used to create new generation forum sites. For more detailed information, you can check the official site of Flarum.
Flarum is still in Beta version.
Flarum is the next-generation forum software that makes online discussion fun. It’s simple, fast, and free.
There are many tutorials on Youtube about how to learn Flarum. You can go to Youtube and watch those videos. Flarum is very easy to use. It is an open-source and developing very slowly.