The bells under your name are BTB bells, which stands for bell tree bells. Most people call it TBT though, it's just personal preference. BTB can be used to buy in-game items, and much more. If your interested in buying/selling things with your BTB bells, you should have a look at TBT marketplace! Although if it's for in game items in animal crossing, that should go in the Re-tail section Your gells go up as you make more posts, but try to make sure you aren't just spamming posts to get your bells up If you have any more questions I would be happy to answer them!
The easiest way is to click on the bell total underneath a user's avatar and prompt the transfer from there. People use TBT to pay for all sorts of items: art, forum collectibles, in-game items, Pok?mon, currency from other sites/DA points, etc. You can check out the TBT Marketplace to get a better idea of the types of transactions that take place.
Your gells go up as you make more posts, but try to make sure you aren't just spamming posts to get your bells up 
