나

나

"I" or "me" (informal).

Here, '나' is used as the first-person singular pronoun in its subject form, as 'I', combined with the subject particle '는'.

나는 책을 읽고 있어.

I am reading a book.

In this sentence, '나' is used as the first-person singular pronoun in its informal possessive/subjective form, combined with the subject particle '가' as '내가'.

이건 내가 필요해.

I need this.

Here, '나' functions as 'me' or the object in the sentence, pairing with the object particle '를' to form '나를'.

친구들은 나를 좋아해.

My friends like me.