I think "il reste" is an expression for "there remains" or "are left' that never changes. http://dictionary.reverso.net/french-english/Il%20reste%20quelques%20bouteilles
Did anyone else translating this into English find the grammar of the second sentence really difficult? Even now I know what it means, I can't recognize how the different components form that meaning. I can imagine how "il" represents the concept of there, as in "il y a" for "there are". I can see how "reste" conveys "remaining, staying". "en" and "quelques" both seem to indicate "some", but I have no idea why there's two words here for that, at the positions they're in. The hover dictionary is giving me "one/a/an" for "uns", and that's just plain confusing. Also, the entire word order of the sentence looks totally alien to me. Would it be best just to learn it in chunks and not dissect so much?
- "Il reste" is an impersonal verb in this context (like falloir/il faut), meaning "there remains"/"there are still"
- "en" means "of them"
- "quelques-uns" means "some" as in "at least two"
Hence (with re-ordering):
- "There remains // some // of them."
"En" when it means "of them" (as opposed to being a preposition meaning "in" or similar) is always placed before the verb (more precisely, in second position after the subject - e.g. je lui en ai donné quelques-uns)
"Quelques-uns" is being used to specify the quantity of them, and therefore is placed at the end of this phrase. You could equally say il en reste deux/beaucoup/plusieurs.
Does this make things any clearer?
Had the same question myself until I checked this at about.com http://french.about.com/od/grammar/a/pronouns_indefinite.htm (Point 2)
Duo may consider "There remain some" correct, and technically it is, but it's not something most native speakers of US English would say. It sounds too formal. A native speaker who wanted to use the verb "remain" might say something like "There are some remaining", but it still sounds a bit formal.
"There remains some" is wrong because the word "some," which in this sentence refers to the plural noun "cakes", needs a plural verb.
You would use the singular verb if "some" referred to a singular noun, even if there were a lot of it:
"Wine? There is some left." (or "there remains some"). There could be many bottles of wine, but the noun "wine" is still singular.
"Cake? There is some left." (or "there remains some"). As with the wine, there could be several cakes, but the question is really asking "Is there some cake left?" or "Is there any cake left?" and the answer is saying "Yes, there is some left."
Wait! You give a very good explanation, but don't forget that there's a difference between cake and wine. Wine is measured in amount (there is some wine, or there isn't--as long as you're not counting the number of bottles), but cake can also be thought of as cakes: and if you walk into the pâtisserie, and want to buy an entire cake, I can imagine the proprietor saying "Cakes? There are some left," or "A few of them are left," where we'd certainly want a plural. I agree that "there are some cakes remaining" sounds a bit stilted, but clearly the plural is needed. (If you're thinking of the situation where one cake, served at a party, is in question, then yes, it would be "Is there some cake left?" But I don't think you'd be starting with the plural Des gâteaux?, as we are here.)
The definite article in "the cakes" (or "les gateaux") would imply that you're referring to some specific set of cakes rather than just any cakes. It's a fairly minor distinction in this case, but it exists in both English and French, so you should preserve it in the translation.