[zo1]

I think they're referring to reciting the alphabet. And reading is much more than just "knowing all the letters". It's context, shapes of words themselves, etc.

I'm not an expert on any of these things, mind you. Just that I learnt to speak and read my home-tongue without ever being able to memorize its alphabet. Now that I think about it, I still can't recite it, yet I speak/write the language fluently.