Yes you can eat cold green beans.
Green beans can be eaten cold or heated as there's no need to cook them.
Green beans are safe to eat raw or cooked.
Raw green beans are actually healthier for you than cooked or heated green beans.
When you eat raw green beans or cold green beans that are not cooked you get more of the health benefits because of the nutrients that remain in the cold green beans.
When you heat up or cook green beans you kill off some of the nutrients in the green beans.
However even cooked or heated green beans are healthy and some of the nutrients remain in the green beans.
I've eaten cold green beans before right out of the can but I prefer to heat the green beans up first as they are more enjoyable when heated.