A push or a pull is a force. A force can make things move. Things do not move unless they are pushed or pulled. Things do not move until some force acts on them.
Magnets push and pull. Magnetism is a force. A magnet is a piece of iron or steel that can push or pull on some metals. Magnets cannot attract plastic or glass. The bigger the magnet, the more force it has.
A magnet can push some metals or other magnets away. It repels them. A magnet can pull some metals or other magnets closer. It attracts them. We say these objects are magnetic.