I don't think anybody knows what it means. There does seem to be some repulsive force in the universe pushing the galaxies apart. Physics has no explanation of what this force could be or why it exists. So that's something that certainly has surprised everybody. I think that back in 1965 people were surprised about the cosmic background radiation from The Big Bang.
People hope to be surprised.
They say that the most unexpected result will end up to be true. Only a fool would think that they couldn't be surprised by the universe. So, we should expect to be surprised. I think the surprises never come in the forms that you expect them. It's different each time, and it always takes way too long.