pardon
You can apologize to someone by saying ‘I beg your pardon’.
‘You’re sitting in my seat.' – ‘Oh, I beg your pardon.’
Some American speakers say ‘Pardon me’.
‘Pardon me!’ said a man who had bumped into her.
British speakers sometimes say ‘Pardon?’ when they have not heard or understood what someone has said.
‘His name is Hardeep.’ – ‘Pardon?’ – ‘I said, his name is Hardeep.’