What does Scout learn from Calpurnia's account of Zeebo's education?

Calpurnia taught Zeebo to read.

"Yeah, Mister Jem. There wasn’t a school even when he was a boy. I made him learn, though."

Did you teach him out of a primer, like us?" I asked." (Scout)

"No, I made him get a page of the Bible every day, and there was a book Miss Buford taught me out of—bet you don’t know where I got it," she said.