My understanding: there are a lot of varieties of coops, consumer coops (REI, the Green Bay Packers, in some respects) are primarily owned by their customers, purchasing coops like ACE Hardware are owned by a group of businesses to increase buying power, and most relevant to this thread, worker coops are where workers own the enterprise. Multi-stakeholder cooperatives blend multiple forms of ownership to try to align the incentives of the enterprise with everyone who has a stake in its success. To me, it sounds really hard to get right, but also transformative if you can, so I’m very interested to learn more!
Multi-stakeholder co-operatives are co-ops with more than one "owner" class. For example, a multi-stakeholder food co-op could be owned by both consumers of the store, and the workers of the store. The co-op's by-laws determines how the groups differ and how the equity share (and patronage dividends) work out.