I don't play the game either, but from what they are saying it sounds like in-game mechanics to prevent you from being 1-shotted by NPC's - i.e. damage that would instantly kill you instead drops you to a very low health . But it's on a cooldown, so it's going to save you someimes, but not all the time. These type of mechanics may get suspended on boss fights as well, depending on the type on encounter it is.

I assume they want to keep the exact workings hidden from the player to prevent players from exploting it.

The Division had something similar in place - it was more like a 'you just fucked up, but we're giving you another chance' thing, but didn't work against certains NPC's like the hunters who would one-shot melee you if you got too close.

I don't play the game either, but from what they are saying it sounds like in-game mechanics to prevent you from being 1-shotted by NPC's - i.e. damage that would instantly kill you instead drops you to a very low health . But it's on a cooldown, so it's going to save you someimes, but not all the time. These type of mechanics may get suspended on boss fights as well, depending on the type on encounter it is.

I assume they want to keep the exact workings hidden from the player to prevent players from exploting it.

The Division had something similar in place.