Ok, so super high level. It's a proposed way of running a mining pool that gives the miners more power to select the transaction set (which transactions make it into the block) instead of the pool operator. It does a bunch of other things too, but that's the one that makes sense in this context. Essentially, more miners creating blocks == more decentralized bitcoin.

You can read a more about it here: https://stratumprotocol.org/ or here: https://braiins.com/stratum-v2

Hope that helps.