This is a very difficult situation.

There are two possible avenues I can think of. You can try to talk with her about it. This assumes you are friends. If this somehow comes up, you can gently nudge that you want her to talk about this and that you are willing to listen. This of course won't solve the problem, but it may be a way for you to be supportive.

Second, talk to the professional confidential counsellor at your school, assuming they have one. You can raise your concern about her parents there. If she is severely beaten by her parents, teachers also have a responsibility there. And eventually this might lead to some intervention. You do not mention from which country you are exactly. Beating children is illegal everywhere in the EU. But in some countries, a small majority of the population may still support things like spanking of children. In the end that may mean a child gets moved away from the physically abusive parents. This is of course very far-reaching. You as a fellow child shouldn't have to be responsible for worrying about all of this. Therefore, talk to an adult you think you and she can trust. If it is not a confidential counsellor, maybe a teacher you do trust? Or maybe your own parents?