No that is not correct. In Dutch "hun" is possesive. "Hen" you can use in combination with "aan". So it is: I give them the book is translated as Ik geef (aan) hen het boek. But it is it is their book!: Het is hun boek! The given sentence is grammatically incorrect Dutch (I am a native speaker and even a lot of Dutch do not use this correctly, so I understand the confusion).