It is a reflexive pronoun used to refer to "they" or "them" when the subject and object are the same.

Symbols at the top of the screen that you click on to give particular instructions

A special area on a laptop or other computer that you touch in order to move the cursor or give an instruction.
- Ester Angulo

is when you look for and find what is wrong with something, like a computer, and try to fix it.

Brothers that born the same day