How does a snake kill a human?

snakes can kill you by constricting, biting with venom, or biting without venom

It depends on the snake. Constrictor snakes will wrap around you and practically squeeze the life out of you. Venemous snakes will bite you and inject venom into your bloodstream, with the venom attacking your vital organs, usually causing fatality. Others will actually spit venom into your eye without biting.