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”.