Oh, about TBT, it is the site's currency and it can be used to buy things for your account within the shop, to exchange ACNL items/villagers, Pokémon, site signatures/banners/art/etc. It's very widely used across here. The exchange rate goes from 2.5-4 million per 100 TBT bells.
Some artists commission with TBT at a 1 million IG bell to 100 TBT ratio, but it's not as common for that anymore, but you could probably pass in doing it if you need the bells to convert later.
And you're totally not ignorant, I was so confused at first too LOLOL.