Favelito is an adult biracial man with brown skin, brown eyes and black curly hair. He's mostly naked, wearing only a pair of green and yellow shorts and covering the lower half of his face with a bandana depicting the Brazilian flag. He carries a pistol in each hand, both of them engraved with the number 55, and usually kicks around a soccer ball.
As his name implies, he lives in one of the Brazilian favelas (slums), where he is involved in some sort of criminal practice, most likely to do with drugs. Despite his cartoonish appearance, he is a hardened criminal who won't show mercy to people opposing him. That said, he can also enjoy a nice game of futebol and so far hasn't been seen shooting people.
Favelito was a well-known face on Brazilian imageboard 55chan long before they made a bunker board on 8chan. The reason he embodies so many negative stereotypes about Brazil (soccer crazy, little regard for human rights, excessive gun violence) is because they didn't design him, but appropriated him from an Argentinian attempt to satirise the Brazilian lifestyle. 55chan took it in stride, slapped two number 55's on his pistols, and made him into a mascot.
Favelito hasn't been seen interacting with many others, but presumably has a neutral relationship with 55-tan. He also seems to have a onesided interest in the mascot of rival Brazilian imageboard BRchan, Kuruminha.