1. Used to acknowledge and ask forgiveness for an action that could cause offense.
2. Used to request that a statement be repeated.
This is generally a term used to apologize for something you shouldn't have done.
We don't really use "pardon" in the US. If you do, people will probably joke that you're trying to sound pretentious or joke that you're British.
Excuses for being late
Saying you can't do something in English