You get a learning opportunity

The learning opportunity is, when triggered, an attack.
If you hit with the learning opportunity attack, you'll learn one copy of whatever is on the icon.
The attack has all attack types: Striking, Sweeping, Oppressive and Back-Handed.
For weight the learning opportunity attack does not use your value in either unarmed or melee, but rather the geometric mean of both those values. Both unarmed and melee are thus relevant for learning attacks.
As the learning opportunity has all attack types, all blocks the monster has up will catch it. You thus need to whittle away pretty much everything before using the learning opportunity.
You only ever get one opportunity per fight, and you do not always get one.