How does the author use description to support understanding of what invisibility is

If they mean invisibility as in unnoticed by the public/popular eye, then the author may give examples or speak of how the topic in question is ignored by most, seemingly invisible/unseen. Anyone would glaze over it without a second thought to the inner meaning or importance it may have.

when alex falls for the charming new boy at school, cole -- a handsome, funny, sports star who adores her - she can't believe she's finally found her soul who truly loves and understands her.  

at first, alex is blissfully happy. sure, cole seems a little jealous of her relationship with her close friend zack, but what guy would want his girlfriend spending all her time with another boy? as the months pass, though, alex can no longer ignore cole's small put-downs, pinches, or increasingly violent threats.  

as alex struggles to come to terms with the sweet boyfriend she fell in love with and the boyfriend whose "love" she no longer recognizes, she is forced to choose -- between her "true love" and herself.

explanation:

the simple predicate of the sentence is camped.