But how is a woman supposed to learn how to be passive, when being passive means doing nothing?

Women are not told to be passive. You're not robots at the man's command. A second-in-command is not a passive automaton, awaiting the captain's orders. They've frightfully busy making sure the ship functions smoothly. But what they also are is a buffer for the Captain so that he can make the hard decisions that actually direct and lead the boat to win or lose, instead of being swamped in the minutiae of day-to-day boat operations.

That's not passive. Not ambushing your husband when he comes home, and feeding him a good meal and rubbing his shoulders isn't being passive, it's relaxing him and making him receptive to engagement. It's making him happy to be around you, and opening him up to appreciating you and listening to what you have to say. There's nothing passive about that.

Conversely, if you're closed off to him or if you're flooding him with your stream of consciousness - there is no empty space for him. He will feel rejected

If you're closed off, he will take that as you don't want him, and go do his own thing. Which becomes a self-reinforcing prophesy.

If you flood him when he's not receptive to it, he will be the one who closes off, just to get some peace and quiet and alone-time.