Magnets create invisible forces that can attract or repel other magnets. The glowing white lines represent "iron filings" lining up with the magnetic field.
Drag the two North (N) poles so they face each other. See how the magnetic field lines push away from each other? That's repulsion!
Grab the little yellow circles on the ends of a magnet to rotate it. Point a North (N) pole at a South (S) pole and watch the field lines connect seamlessly!