Faber states three features of books. First, they have "quality." Faber means they are a reflection of real life. They speak of both the evils of humanity as well as all of the good things humans do. But that is the job of books: to reflect life. Second, books require "leisure." People have to take time to read and digest the books. The fast-paced lives that the people in the novel lead leave no room to slow down and read or reflect on life. Finally, Faber states that the third quality is "the right to carry out actions based on what we learn from the interaction of the first two." He means that people must not only read books that reflect life and take time to think about what they have read, but then they must process what they have learned in their own lives If you think about it, Montag is doing just this, though he doesn't really realize it yet.
This of it this way- let's say you read about book about the holocaust in Nazi Germany. You have had time to read it and likely have been shocked by the brutality and genocide practiced by the Nazis. Now, as a result of having read the book, you have a greater understanding of what those who were persecuted when through. You may also be more compassionate for people who are being persecuted today. That is why Faber argues for books.
It's not just about the books themselves but what's in the books.