In the book, it is used as an insult to someone.
Arschloch means "prick."
My Own Sentence
Her best friends begged for her not to stay with that Arschloch, who treated her like nothing.
Word, Page Number, and Part of Speech.
The word: Arschloch
Page Number: 91
Part of Speech: noun / sentence its used in: "Don't wave to that Arschloch," she said.