In computers, data refers to information or facts that are stored, processed [manipulated or worked on], or transmitted by a computer system.
For example, when you type a document on your computer and save it, the words you typed are data. Similarly, when you take a photo with your phone and save it, the image is also considered as data.
Very Simple Definition:
In computers, data refers to the information or facts that computers use.
For example, when you write a message to your friend using a computer, the words you type are data. Likewise, when you play a game on your tablet, the pictures you see are also data.