Translation:There are nine million people living in Sweden.
For non-native English speakers who think that ONE of the English constructions here is weird... Yes, you're right, it is weird. That is, "In Sweden live 9 million people." To be clear, it's not wrong, it's just a bit non-idiomatic. On a personal note, I would appreciate this verb in second place construction, but I would also think "I wonder why they chose that construction..."
I realise that Duo's default translation is "There are nine million people living in Sweden." This is basically the -only- way you would ever put this sentence in English. There are other ways that are technically correct (and sit closer to 'side by side' with the Swedish), but they are unusual, such as the above one that starts with "In Sweden..." So you could say "Nine million people live in Sweden." - no problems. "There are nine million people living in Sweden." - also no problems "There are nine million people who live in Sweden." - fine, I'm not sure if the "who" technically changes what we're actually saying but it certainly doesn't make a big difference. "Nine million people are living in Sweden." - fine. It sort of sounds like they are temporarily, but it doesn't mean that. "In Sweden there are nine million people." - it's not quite the same thing but when talking about a country or city, we would only assume that you meant "people who live there". We wouldn't think that you meant there are 9 million people visiting for a festival or something, unless you were talking about a building or a park and a number of people in the thousands.
This is just for the non-native English speakers. I know the course moderators know all this stuff.
It corresponds to "there". In Swedish we use "det" for "there" in "there is" and also for "it" in "it is". I can be confusing for native English speakers.
Off topic: I am studying Danish on Duolingo and i just learnt that they distinguish between "there" and "it":
there is = der er (Dan) = det är (Swe)
it is = det er (Dan) = det är (Swe)
No, unfortunately not! But I'd love to know :). Maybe you can ask one of the "skåningar" from this thread?
And yes, I mean there is = det finns. The tricky thing is that we don't always say "det finns" but "det är", e.g. "there is a fly in my soup" - "det är en fluga i soppan". I once tried to figure out when "det är" is ok and when you have to say "det finns". It gave me a headache though and I decided never to think about it again.
I think I've had that headache too. We've had some discussions here where people have offered different solutions, I think the closest one is that if something is only temporarily somewhere… There was also one with eggs in a box, where I figured we say det är 12 ägg because it's really the number that counts, (hehe), not their presence in the box. But I don't think we've covered it totally.