I can give you many answers for this question, but it depends on the level of your studies. So I'm giving you a basic answer.
Answer:
Computer is a versatile device, as it can be used for many purposes. Such as Printing, Listening to music, Entertainment purposes, Programming, Animating, business purposes, and much more.
Computers are used for complex purposes too.
Suppose, controlling Satellites, Navigating Aeroplanes and more.