As (lightly) represented in the film, yes she was a call girl. However, interestingly enough, Capote had called her an “American geisha” in a ‘68 Playboy interview. Then again, there are plenty of differences between the novella and the film (a big one being that “Fred” is gay) and I do suggest everyone read the novella as well.

I haven’t seen the movie in quite a while, but what I can imagine she meant by that is that she received a substantial amount of money from her talks with Sally, and that money to her is like candy to children. You’re very welcome, and I hope that answers your question!