Magneto is a very powerful mutant in X-Men, Magneto power is that he is able to generate and control magnetic fields. In the beginning Magneto and Professor X are friends and their different philosophies cause a rift between these characters. Magneto believes that he and other mutants are a superior than humans and they are the future. Magneto was already really powerful but after he makes a helmet which protects him from Professor X to ever get into his head, he becomes even more powerful and dangerous.
The whole time there is cat and mouse chase between these one so call friends now turned enemies. Who is right between these two? Well, that depends on whether you are a human or a mutant who has only suffered in the hands at the hand of humans. Is there a chance that both of these characters can come to common ground? For that answer you need to watch all the X-Men movies and read comics.