I think that means WeChat in the sense that in China WeChat isn't just an communications app, it's an app through which many/most people do a great deal of transactions -- shopping, p2p payments, paying utility bills, customer support, ride hailing, banking, etc., It encompasses what about 10 apps in the US do. You cannot understate how pervasive its use is in ways that have little to do with social media. That's what Elon wants to turn Twitter into.