After winning a judgment, Google would have to go to court in Vietnam and ask for the judgment be enforced. The court would look at wether proper notice was given, the jurisdiction was proper and that the underlying conduct was something you could sue for. They may also look at the award to determine it isn't excessive. If they're satisfied the court can then issue an order to enforce it.
This all depends heavily on how the Vietnam legal system works, which I have no idea. Obviously every country has their own quirks and processes.
I’m guessing that’s the weak point, but I don’t know how that would work exactly.