some animal made a few scratches on the bark of my hornbeam, i think it was my parents cat do these scratches heal themselves overtime or do they stay forever
If the scratches are vertical, that's what I imagine with cat scratches, they should heal pretty easily without any intervention. If they are not vertical, I would put some grafting paste or petroleum jelly on them. If you don't, large portions of the cambium are liable to dry up and die.
How long they remain visible depends on what kind of tree you have. A deciduous tree with smooth bark will show the scratches much longer than a tree with rough bark. It also depends, of course, on how deep the scratches are.
In any event, you should carefully clean the edges of the scratches so there's no raggedy bark hanging on to the scratches.a
I will try to get a photo later but the scratches are not deep they are just a small layer of the outer bark about five or six scratches in all the tree already has natural cracking of the bark which I imagine is what the scratches will look like later
That doesn't look deep enough (to me) to have caused damage to the living part of the tree (cambium layer) so it won't exactly "heal" but I think it should weather, change color to blend in with the rest of the outer layer, and crack as it ages such that it won't be noticeable.