A magnet can pull some things made of iron. A paper clip may stick to a magnet even when you do not push it. This happens because there is an invisible force around the magnet.
The area of this force is called a magnetic field. A magnet has two ends. One is the north pole, and the other is the south pole. Opposite poles pull together, but the same poles push away.
Not all things stick to magnets. Wood and paper usually do not. Some metals with iron feel the magnetic force strongly.
That is why a magnet can pick up paper clips or small nails.