Books can mean so much more than just be symbolic for learning and knowledge. They can show emotion, conflict, setting, characterization. They can foreshadow too. It’s all in what and how you use the book(s) in your story. Any detail that you include about the book can make your writing more purposeful and add nuance to your characters and story.
Books and all their little details can SHOW emotion, personality, world views, societal views, without TELLING. And readers are smart– they pick up on those clues instinctually.
What’s the title of the book in your story? How is the title important to the plot, character, and conflict? Is the book old or new or ancient? Honestly, who doesn’t love ancient wisdom? Why exactly is the book forbidden? Or hidden? Or locked away? Or forgotten? What does it really say about the characters or the setting or society? Is the book well-loved, dog-eared? Or is it in pristine condition? What extra clues do you want to give your readers by including a book in your plot?