Meaning of “I beg your pardon.” - Learner’s Dictionary

I beg your pardon.

formal spoken

used for saying 'sorry' when you have made a mistake or done something wrong:

I beg your pardon - I thought you were speaking to me.

used to show that you strongly disagree or that you are angry about something that someone has said:

I beg your pardon, young man - I don't want to hear you speak like that again!

(Definition of “I beg your pardon.” from the Cambridge Learner’s Dictionary © Cambridge University Press)