I dont know why the faces of my model look weird
What faces? The invisible ones? May be you had hidden faces (alt + H for reveal hidden ones) or inverted normal faces (alt + N -> flip (normals) or shift + N to recalculate (normals)). Good luck.
What faces? The invisible ones? May be you had hidden faces (alt + H for reveal hidden ones) or inverted normal faces (alt + N -> flip (normals) or shift + N to recalculate (normals)).