Meaning of “pay sb/sth back” - Learner’s Dictionary

pay sb/sth back

phrasal verb with pay uk us /peɪ/ verb (past tense and past participle paid)

B1 to pay someone the money that you owe them:

Only borrow money if you're sure you can pay it back.
I lent him $10 last month and he still hasn't paid me back.

(Definition of “pay sb/sth back” from the Cambridge Learner’s Dictionary © Cambridge University Press)