Yes weasels do eat snakes.
Snakes are a part of a weasels diet and when they see snakes the weasels will attack, kill and eat the snake.
Weasels also love to eat other things besides snakes such as frogs, rabbits, birds, voles, mice and worms and other insects.
If you have mice or snakes around your home or property then having weasels around is a good thing because the weasels will eat the snakes and mice and keep them away from your property.
When I lived in a rural part of our town I had weasels around the property and never noticed any mice coming into the house.
I would see the weasels eating the mice so that was a good thing.
I also saw the weasels killing and eating snakes which I hate snakes so that is good as well.