So the Sun is larger than the average star. The sun is large enough to easily contain all of the rest of the objects of the Solar System. It produces energy at its core, by nuclear fusion of hydrogen into helium. The most obvious visible feature on the more or less uniform surface of the Sun is the sunspots. Galileo is often credited with their discovery, although they were sometimes seen before the invention of the telescope.
Sunspots are like storms, caused by magnetic fields, which are often larger than the Earth.
They appear dark because they are slightly cooler than the rest of the surface. And we see prominences, explosions of gas streaming from, and into, the sunspots. There is also a general outflow of gas from the sun, called the solar wind. This increases during maximum sunspot activity. The Sun rotates, in the same direction as the planets.