This vote is interlinked with the pDAO Charter and Inflation & pDAO Budget Allocation votes -- if any of the 3 fail, all will be considered failed (and none will take effect).
This snapshot will be voted on by the oDAO, not the pDAO.
The oDAO charter establishes what the oDAO is, what its values are, how it will function, and what its responsibilities are. I don't think it can be summarized further than the RPIP, so please read the RPIP.
oDAO members will vote by using rocketpool node send-message from their oDAO node and sending a message to 0x0Da0000000000000000000000000000000000000. The data of the message should be utf-8 encoded and say "seatname votes For/Against/Abstain on RPIP-24". If there is more than one vote from a seat, the last vote in the vote window will be counted. In order for this vote to pass, at least 51% must vote "For" (10 votes). Anyone will be able to trivially verify the votes on Etherscan based on the signing address and data interpreted as utf-8.
pDAO members MAY or MAY NOT use the For/Against/Abstain buttons here to signal. This is purely a signal; pDAO votes and quorum will not impact the result in any way.
Please read the full RPIP here. You can read discussion around this in the forum thread.
For reference the oDAO addresses that can vote are: