So I was asked to learn someone's else role which is pretty technical and it take a while to learn and I am not absorbing the information well because I am trying to keep up and be more efficient with the job I was hired to do instead of learning a entirely new role that does not overlap much with what I do.
Supposedly, this is to cover the person when she is on vacation, but the problem is, there is too much to learn and I don't really have the time to do her work in order to get some practice so I can retain the knowledge since her work deadlines conflict with mine.
How do I inform the managers that I can't handle the extra work?