In Chinese, the same sentence would be: 我們點的菜，還要多久才會端出來?

It means: How much time do we still have to wait before our food is served? Customers usually say this when they have to wait a long time to get their food after they have ordered it, perhaps because the restaurant is full and there aren't enough waiters.

They want to know the amount of time it will take until the waiter gives them their plates. "How much longer" is an idiom that means "How much more time will pass".

Grammar note: Your question should be, "What does this mean?" or "What does _____ mean?"