Whenever you watch a Korean drama or movie, if you listen carefully, you will hear the girl call her boyfriend “oppa”. It’s a Korean word for a female’s older brother. There is no direct translation for this in English, so if you look at the English subtitles, they will write the man’s name instead. So now you know! 🙂
As for a male’s older brother, the word “hyung” is used. Thus, you will hear a man calling another man whom he is quite close to “hyung”.
오 빠 (Oppa) – female’s older brother
형 (Hyung) – male’s older brother
Even if the woman is older, but she is in a romantic relationship with a younger guy, she calls him “oppa”.