Ok so what are the voidbringers? (Am I dumb?)

I’ve read all of the cosmere (minus the novellas) and am doing a reread of Stormlight. I’m almost done with my reread of Words of Radiance. I’m noticing so many more details and understanding so much more this time….but I’m actually still very confused on what exactly a voidbringer is! In one of Dalinar’s visions he fights that weird black sack monster thing with the fire poker. Did he consider that a voidbringer? What about those giant rock monsters later in the series that you can only hurt with a shardblade? Or are voidbringers related to the fused or the singers? And what exactly are the fused? They take the singer bodies right? It’s their “old gods”….were these one of the unmade (ba ado mishram or something?). And the cycles of desolations followed by rebuilding….what exactly were the desolations? Was it the fused fighting the knights radiant every time?

I’m still so confused 😅