Meaning of “make it up to sb” - Learner’s Dictionary

make it up to sb

phrasal verb with make us uk /meɪk/ verb [ T ] past tense and past participle made

to do something good for someone because you have done something bad to them in the past:

I'm sorry I missed your birthday. I'll make it up to you, I promise.

(Definition of “make it up to sb” from the Cambridge Learner’s Dictionary © Cambridge University Press)