"What does the 'ya' at the end of the term 'oppa ya' mean when used?" "Ya"(야) and "Ah"(아) at the end of a name or family word don't have any meaning. It is just a suffix that is always there when you call someone. For adults, one must use -씨(Mr) or another title word except between close friends. For children and teenagers, 아(after a consonant) and 야(after a vowel) are used. This 아/야 is always used when calling children/teenagers by name(영훈아, 지혜야). For older brother/sister (오빠, 누나, 형, 언니), 아/야 is actually not used often. Just calling "오빠", "누나" without 야 is more common and natural. 오빠야, 형아 are sometimes used (if the age difference is small) to show affection. One never uses it if the other person is older by more than a few years. In poetic language this is conveniently extended for personification of things. For example, 비야 내려다오 (literally "Rain, please fall") is common and natural.

In this case, "ya" is just something added after someone's name when you're calling them. It has no real meaning. Maybe sort of "hey x". I don't suggest using it with a boss or the President. I believe it's informal.

오빠 - Standard language 오빠야 - Patois( im not well in english)