Answer: the quality or condition of being insignificant ; lackof importance or consequence
Explanation:
"she" would be the pronoun.
You can rewrite this question as "She is your best friend?"
So in that case, "she" would be the subject.
In English, you just switch around "is" and the subject to make a question and make it sound Englishy
PS in Italian (and probably other languages) you would just say "She is your best friend?"
It would be imperative because it shows vital importance
In order to find theme look for what the story is trying to teach you. You could also look for the life story the author included.