"Hij wil zijn boek kunnen lezen."
Translation:He wants to be able to read his book.
In Dutch the main verb is usually at the end of the sentence, so 'lezen' should be at the end. The other way around does not sound natural, but is not wrong.
"Hij wil zijn boek kunnen lezen." sounds much more natural to me.
However, I believe this might be different in Flemish.
These sentences are starting to not make sense anymore. "He wants his book to be able to read" Immediately came to mind but was wrong.