He's talking about learning that makes you operational. If you can speak with someone, then you've learned language. If you can get a computer to do something, then you've learned some programming.
The equivalent for biology would be to grow a plant or a few plants and animals successfully. That's operational at a certain level, you could also be operational at a lower or higher level.
No, it doesn't necessarily need to be applicable, it just needs to be testable. The size of the Earth for example may not affect you directly in any way, but it's something you can verify to some degree of precision. But if you just read about it, can you really say that you know it? What if all you believe about the size and shape of the Earth is from what you've asked an LLM? Do you still know it?
EDIT: Perhaps not the best example, because the size and shape of the Earth are data that are repeated often enough that an LLM would be unlikely to quote it grossly incorrectly, but I think my point still comes across.
I’ve been burned by this enough that I no longer say that I’ve learned something if my only interaction with it is explanation from books. You can get snippets of knowledge and a framework of understanding, but true learning only comes with deep interaction of the concepts (practice, simulation, experiments, observations) and not merely reading.
The equivalent for biology would be to grow a plant or a few plants and animals successfully. That's operational at a certain level, you could also be operational at a lower or higher level.