I understand it to mean “I’ll explain something to you in my words, now you describe it back to me so I can evaluate whether the right message came across”.

Helpful exercise if you’re honing a pitch, because first listen understanding is key

I had the same question, and I asked GPT-4: https://pastebin.com/9RxenXMk

The phrase has zero hits on Google, though “reverse pitching” is apparently a thing.