To not give up —————————————————————————
The underlined term (flies) used verb+es which is used to describe the verb that still being doned regularly.
If the verb is currently being done , the verb will use-ing , if it's a plan in the future, we will see 'will' before the verb and the verb will not use -es
hope this helps
"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?"