It’s in the help if you search it.
Generally the kanban stuff is going to be more reactionary, so someone sees that the need to make it on the shop floor because the reserve quantity is low (usually a bin or “spots” on the floor). Instead of using push signals from the system, it’s a pull signal from somewhere. Like, we need to ship these out, so I’ll go “make” them. Or we don’t have the 5 sitting on the shelf that we want to have for a minimum, I’ll go make some to replenish. Generally the parts that need to go into it would have a minimum on hand, and you would drive your PO’s that way, because you don’t have scheduled jobs to drive demand for the parts that go into it. That’s just how the concept of Kanban works.