Meaning of “p.m.” - Learner’s Dictionary

p.m.

( also pm) uk us /ˌpiːˈem/

A1 used when you are referring to a time after 12 o'clock in the middle of the day, but before 12 o'clock in the middle of the night:

Opening hours: 9 a.m. - 6 p.m.

(Definition of “p.m.” from the Cambridge Learner’s Dictionary © Cambridge University Press)