Honest question and maybe it's because I grew up without books… What values do books have if you cannot read? I started to learn how to read at 6. Are those picture only books?

No they are not picture-only books. They have simple stories, which are for parents to read to their children. Reading stories to children before they can read is a very, very old tradition :) (think fairy tales)

(edit - you've gotten several responses but I will say that you are correct that this sort of thing does not happen in all households; that's one reason this program is great, because it encourages this behavior)

Not to be snarky, yes picture books, but also, adults do often read books to children.

Someone, typically a parent of guardian, reads them to you while showing you the words. After reading the story, they might go back and walk you through each word, how it's said, and its meaning.

Not only do a lot of kids learn like this, but for instance the little Polish that I know how to speak and read I learned like this as an adult with the help of a native speaker.

Are you implying there’s a chicken-and-egg problem with books? How are you supposed to learn how to read without written material?