"The book is yours."
Translation:Het boek is van jou.
No, "het boek is van jou" means "the book is yours" (if you want to say "the book is about you", it should be "het boek gaat over jou"). There is no major difference in meaning between "het boek is van jou" and "jouw boek", but one is a full sentence and the other is not, just like "the book is yours" and "your book".
Just depends how you want to say it. Van means 'of', 'from', and even 'by', depending upon context. In this situation, the closest to their english sentence is: 'het boek is van jou', literally "the book is FROM you" or "the book is yours". It's a roundabout way for describing ownership, but it is very common.
"het is jouw boek" would be another way to write ownership, but that's technically a different translation ("it is your book" vs "the book is yours"). See the difference?