From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The Sun (太陽, Taiyō) is the star at the center of the Solar System. It functions similarly to its real world counterpart, providing heat and light to the beings of Planet Earth. It is shown as a living being with a face in the Dr. Slump series, but this is not carried over to the Dragon Ball franchise. The word "sun" is sometimes used for other stars.
The Kaioshin Realm had several suns.
The Next World had a sun.
The Sun wore sunglasses, ate ice cream, and even complained about the heat.
The Sun had a minor role in several films. Lucifer wanted to get rid of the Sun so that he could take over Planet Earth in Dragon Ball: Sleeping Princess in Devil's Castle. Coola in Dragon Ball Z: Cooler's Revenge (although he was able to barely escape), Broly in Dragon Ball Z: Broly: Second Coming, and Baby in Dragon Ball GT were killed by being blasted into the Sun. Slugg blocked out the Sun using a huge cloud because his henchmen could not stand sunlight for too long.