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

set sb/sth back

phrasal verb with set us uk /set/ verb present participle setting, past tense and past participle set

to make something happen more slowly or later than it should:

The heavy traffic set us back about half an hour.

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