It has electrically charged gases that generate areas of powerful magnetic forces. These areas are called magnetic fields. The Sun's gases are constantly moving, which tangles, stretches and twists the magnetic fields. This motion creates a lot of activity on the Sun's surface, called solar activity.

What solar activity means?

the sum of all variable and short-lived disturbances on the sun, as sunspots, prominences, and solar flares.

How solar activity affects the Earth?

The Sun's irradiance has its greatest effect on Earth's upper atmosphere, while the lower atmosphere insulates Earth from the increased heat. If the Sun were driving Earth's warming, one would expect to see that upper atmosphere getting increasingly hot.