getting into kpop is a lil confusing because of all the new words and cultural stuff, so here are some useful words you'll probably hear a lot:

• hyung (형): how guys call guys older than them
• nuna/noona (누나): how guys call girls older than them
• oppa (오빠): how girls call guys older than them
• eonni/unni (언니): how girls call girls older than them
• dongsaeng (동생): people younger than you, doesn't matter the gender; if you want to be specific about their gender like "a younger female person(???it sounds weird i know sorry???)" you can add "_yeo(여)_" at the beginning and if you want to say it's a younger guy, add "_nam(남)_", so it could be either yeodongsaeng여동생 and namdongsaeng (남동생)
  • though this one you don't really use to "call" someone, if that makes sense? hyung/oppa/eonni/noona you can put after someone's name or just use it alone and call the person, but you don't do it with dongsaeng, they might say it sometimes to be funny or idk but in general it's awkward
• jingu/chingu (친구): literal translation is friend; someone born the same year as you; has the same age as you
• sunbae (선배): someone who's more experienced than you. uhm, like bts debuted in 2013 and super junior is a group that debuted in 2005, so SJ is BTS's sunbae and BTS will talk formally to SJ and treat them very respectfully (it's not used just on kpop; someone more experienced than you at work is also your sunbae, a senior at school when your just a freshman or whatever is also your sunbae and so on, you'll hear it on dramas too)
• nim (님): nim is a korean honorific that just shows someone is....very wow??? lmao idk how to explain, like the nim honorific shows someone is very skilled and stuff, for exemple seonsaengnim (선생님) (teacher), or PD-nim (producer); it just shows respect generally
• hoobae (후배): the opposite of sunbae? someone with less experience, if i'm a senior and you're a freshman, you're my hoobae; following the SJ x BTS example: BTS is SJ's hoobae

ps: you call your siblings by those 5 at the beggining too, so sometimes "hyung" or "oppa" would be translated as "brother" or "bro" or something, which is not wrong if you're actually siblings, but yeah... the hyung/oppa/noona/eonni are generally terms they use towards someone older to show some affection. there are some polite ways to call someone older than you without using these, but if they're close, they usually use them!

idk if it was too confusing, sorry aaa!! hope this helps ♡ once you understand how stuff works you'll remember the words easily lmao until then: fighting!