Nichkhun not only speaks thai korean and english he speaks mandarin chinese to. Proud there is a Thai mixed asian in a kpop group , all the others i know from kpop groups are koreans ^.^
Thai is his mother language because he is thai. So thai language doesnt count as a language that he capable of. He could speak korean, english and japanese is what is count. If someone could speak their mother language is common. But if you are able to speak other language outside your mother language is good.