Breakdown of kanojo wa koi no uta o kaita.
Questions & Answers about kanojo wa koi no uta o kaita.
は marks 彼女 as the topic of the sentence. It tells you that the sentence is talking about her and then says something about her.
So the structure is roughly:
彼女は = as for her
恋の歌を書いた = wrote a love song
This is different from が, which would put more focus on who did the writing. With は, the sentence feels more like you are already talking about her, or contrasting her with someone else.
Yes. 彼女 can mean she / her, but in other contexts it can also mean girlfriend.
In this sentence, because は marks it as the topic and the rest of the sentence describes an action she did, learners will usually understand it as she. Context decides which meaning is intended.
