A superuser is like the boss of a computer. Just like how your parents are the boss of your house and can do things like open or close doors, turn lights on or off, and keep the house safe, a superuser can do similar things with a computer. These are really important things that your parents or other trusted adults might do to keep you safe or help you accomplish something.
On a computer, a superuser has special powers to change things that other people who use the computer can't. They can install or delete programs, change settings that affect how the computer works, and even see what other people are doing on the computer. It's important to have a superuser because they can help fix problems or make sure everyone is using the computer fairly and safely.
Just like how you might have a password to keep your favorite toy safe, a superuser also has a special password to keep other people from using their powers without permission. This is really important because just like how you wouldn't want someone to take your toy or make a big mess in your house, a superuser doesn't want someone to accidentally or purposely break the computer or steal important information.
Overall, a superuser is like a big helper who is really good with computers and has extra powers to keep things running smoothly and safely.