Homie would be a friend, someone that you spend some time with. As a flatmate, or the ones that are into gang cliques.
Many Latino gang members that were deported from California back to countries in LA. Call each other homies, word borrowed from the English language.
It´s the same as saying "bro" some years ago. And it is, of course, slangy (or colloquial depending on to whom you are talking to).