This is the 364th most frequent Italian word.
libro
"Libro" means "book" in English.
Here, 'libro' is referred to as the book being the larger work containing chapters; the focus is on a specific chapter.
Questo capitolo del libro è particolarmente emozionante.
This chapter of the book is particularly exciting.
In this case, 'libro' is used as an object to represent a literary piece being actively created by someone.
Sto scrivendo un libro sulle tradizioni culturali.
I am writing a book about cultural traditions.
In this sentence, 'libro' is used as a common noun to refer to a reading material.