In reality, it is more of a manual than an official guide or an artbook. It presents the license, the main characters and the kingdom of Hyrule. This is followed by all the specificities of Breath of the Wild: the sanctuaries, gameplay elements, secondary characters, the bestiary, the guardians and their powers.
Nintendo being as it is, the myriad of amiibos (physical figures that interact with the console and the game) are also presented.