If the open textbook you are working on is a new creation, it will be released with a CC-BY 4.0 International license.
The Project Manager you are working with will add a page called “About the Book” to the Front Matter of your final work. It will include the following sentence about licensing:
Our open textbooks are openly licensed using a Creative Commons license, and are offered in various e-book formats free of charge, or as printed books that are available at cost.
Information about licensing is added, by the Project Manager, to the book information section of PressBooks. This information appears at the bottom of each web page of the online version.