"There are many factories here."
Translation:Det finns många fabriker här.
Is there a difference when using "många" versus using "flera"? Is one or the other used more commonly in certain situations or in relation to specific words or..?
Många is more than flera. Flera fabriker says there are more than two but probably less than about ten (my opinion). Många could mean hundreds.
I always read manga as many, I don't know if it is a good idea to look at it that way though.
It's a good idea.
många = many
mycket = much flera = several
några = some/a few
Without saying "that's just how it is", why wouldn't we use " de finns" since it's plural?
It's always det in presenting constructions – the kind of construction we have here, where we introduce a subject. It's like it in it's raining, – this det does not refer to the latter part of the sentence.
Much longer text about this here: https://www.duolingo.com/comment/9708920
Would saying "Många fabriker ligger här." make a difference worth mentioning?
Without context, it sounds a little bit awkward to phrase it that way. It is not an accepted answer right now and personally I dont think it should be. The sentence is grammatically correct in itself though. (But I just added "Det ligger många fabriker här")