Look at its eyes. If they are round circles, it isn't venomous. If they are slanted, it is. I'm not sure what kind of snake it is, but really, all you need to know is if its venomous or not. Even if it isn't venomous, its acting aggressive because it knows its small enough to be eaten and it thinks you are a predator.
I currently have 4 snakes, one being a Ball Python, Grey Banded King Snake, Dumeril's Boa and Honduran Milk Snake. I've had in the past another Ball Python, 2 Red Tailed Boas, 1 Brazilian Rainbow Boa, 1 Jungle Carpet Python, 2 Kenyan Sand Boas, 1 Corn Snake, an emperor scorpion and a leopard gecko.