Literally: Why is he like that
Also: What’s with him?
Pronouns aren’t really used in Korean, but 쟤 functions as he/she.
You may know ‘왜 그래’ like ‘what’s up with you’ or ‘why are you being like this’. This is the same thing. 왜 means ‘why’, and 저래 is like 그래. I was not given a more detailed explanation of that word.
I’m the opposite
난 is the informal 나, meaning ‘I’ and the topic particle ㄴ/은.
반대 means ‘opposite’. It can be used to say you have the opposite opinion, or it can be used to say something is in the opposite direction, the same as English. The -야 at the end of 반대 is the informal conjugation of -이다, meaning ‘to be’.
It’s bad / not good
별로 is normally seen as ‘not really’, when used with a negative conjugation. Like ‘그것 별로 안해요’, meaning ‘I don’t really do that’. However in certain contexts it can just mean ‘bad’. Like in this one.
-야 is the informal conjugation of 이다, ‘to be’.
This one was odd to me, so I ran it by a native before posting!
A simple one! 관심 is ‘interest’. 없다 is the dictionary form meaning ‘to not have’. So literally this is ‘I don’t have interest’. But naturally it is ‘I’m not interested’.
in context usage
(Don’t worry…it’s a friend ~)
응 is the casual form of 네, only used informally! 아니야 is a combination of the stem of 아니다 (meaning, essentially, ‘no’) and the casual conjugation of 이다 (to be). This could be translated to ‘yeah, no’ or ‘yeah it’s not’.