"This is a book about him."
Translation:Bu onun hakkında bir kitap.
bu kitap onun hakkında: this book is about him
although very similar, those are different things
I will try to explain with my limited grammar: In this sentence "to be a book about him" is the predicate, the action of the sentence. And the subject is "This". To give the same meaning in Turkish, we have to translate the whole predicate " onun hakkinda bir kitap" and complement it with the subject, "bu" and the sentence becomes: "Bu onun hakkinda bir kitap".
Instead if the sentence to be translate was "This book is about him", the predicate would be "to be about him", translated it would give "onun hakkinda", and the subject would be "this book", translated it would be " bu kitap" , hence the final result would be "Bu kitap onun hakkinda". Hope it makes sense :)
I believe the confusion mostly arises from dropped words and suffixes for "to be" in Turkish. In this example the old fashioned way of writing these sentences would be "Bu onun hakkinda bir kitaptir" and the other sentence would read "Bu kitap onun hakkindadir" -dir indicating the predicate more clearly.
I will remind you, modifiers always come before the things they modify in Turkish :D
"which book" -- "The book about him" "about him" = "onun hakkında"
Ergo "onun hakkında bir kitap"
"hakkında" is also a postposition (there are no prepositions in Turkish). If you wanted to say "about a book" the postposition would come after/post "a book."
So, "bir kitap hakkında"
It just takes some reprogramming of the mind to understand it. :)
Sorry, I am confused because you said that modifiers always come before but then you said there are no prepositions... Can you clarify?
Nope. That would be "This book is about him" which is an ever so slightly different sentence in English :)