This is Audiobook, the mod that reads books out loud so you can continue to go about your adventures while listening to them. It makes use of Minecraft's Narrator feature to do this.
To use Audiobook, hold a book in your hand and press H (configurable). To stop an audiobook that is playing, press J (also configurable). You can also use these keys while the book is open, so it can be used with books that are on Lecterns. You do not have to continue holding the book once it's playing.
This mod is client side only, so you can use it on servers that don't have the mod installed.
To report issues or request new features, use the issue tracker. Do not ask me to port to different Minecraft versions. For questions and other discussion, feel free to join my Discord.
Mod spotlight (with Textbook):