Quantum electrodynamics that electromagnetic interaction force between two particles is the nature of the same constantly exchange the result of the photon.
Two electrons close to each other and eventually bounce off because of electromagnetic force, what happened here?
The original two electrons in exchange of photons.
Imagine two people of the skating rink, they kept trying to put a ball to go to, from a person's hand to another person, so they will be far from more and more, seems to have a repulsive force between them.
In the electromagnetic force, the ball is photon!
Magnet has the S pole and N pole, if two magnetic S pole or N pole together are mutually exclusive.