In order to function at a most basic level in a given society (which I do not yet in the South Korean context), it is good to know the basic words of courtesy — the equivalents of “Excuse me”, “Pardon me”, “Nice to meet you”, “Hello”, “Goodbye”, etc..
Today we’ll talk about how to say “I’m sorry.” Between talking across cultural / language / expectation differences, and just spending time with individuals you might not know well, being able to apologize is a very important tool in the toolkit.

Mian (mee ahn) is the root of one way of apologizing in Korean. Often you’ll be saying this formally, so Mianheyo (미안해요) would be what you would say to apologize. If you don’t need the formal, usually you’ll say “Mianhe” 미안해.
For a more comprehensive coverage of apologies (plus pronunciation!), see Sweet and Tasty TV’s coverage of this: