Magnetic force fields are caused by charges in motion. Sunspots have strong magnetic fields. More often than not, sunspots come in pairs. One spot is the North magnetic pole, the other is the South. Scientists can trace the magnetic fields of sunspots using a device called a magnetograph.
Magnetic fields act a bit like rubber bands.
When you stretch or twist them they can snap back violently. With a rubber band all you get is a hurt finger. When a sunspot magnetic field you can end up with a tremendous solar flare. Scientists predict when flares are going to happen by looking at their magnetic fields . When the fields are simple and untangled, like a bar magnet's, flares are unlikely.