Translation:There is not much curry.
It does sound a little weird, but if you say "There's a little curry" it doesn't sound weird at all. That's what I put and it marked it as wrong. I think it should be allowed.
Also, since we're learning Japanese here and not English here, I feel like they should allow "There's little curry" because it's grammatically correct.
"little" and "a little" are different though.
"There is little water in the well" means we should be concerned that the well might soon dry up. "Little" answers "How much?", as opposed to "a lot".
"There is a little water in the well" means "we're good: there is some water in the well, so we should have enough for now". "a little" here answers the question "Is there any water?". The opposite answer would be "no, nothing".
"a little curry" and "little curry" would work similarly: "There is a little curry in it, so beware if you can't stand curry" while we'd have "There is little curry in it, so don't worry, there is not a lot of it".
I was thinking about this, and I think I figured it out... when we use "little" in English to describe quantity, we usually use another word along with it, like "very little".
To support this, there is another example in Duolingo that goes like "とてもすくないです", and it is translated as "very little".
I absolutely hate this lesson because I spend so much time trying to remember what duolingo has decided is the ”correct" translation. And, it's inconsistent from question to question!! A couple questions ago I used "not much" for sukunai and it was incorrect. Now it's the right answer. What?
But it means the same in this case, so should be accepted. What is interesting is, in English we might say "We are almost out of curry", but it is not said in as personal ("we") a manner, and therefore, more polite. Otherwise, to Japanese, it might sound like "you want to get the last of our curry" and therefore make the request sound inconsiderate.
sukonai = adjective sukoshi = adverb
すくない typically used to imply there isn't much left, whereas the word すこし refers to quantity, for this reason, your answer would be incorrect.
多くない is the negative conjugation of 多い. 多い by itself means "numerous" or "many", so 多くない means "not numerous" or "not many".
少ない is an い-adjective that means "a little" or "few" and is unconjugated. In other words, 少ない is the positive form of the word while 少なくない is the negative conjugation meaning "not a little" or "not a few".
Because of the word すくない. It is an い-adjective, which means that it has its own set of conjugation rules. If we wanted to use あります, then we would need to conjugate すくない to すくなく and attatch that to あります. That being said, it sounds weird using すくない that way just to use あります. The grammar pattern here Aは/がBです is sufficient to say "A is B.", or "[Curry] is [not a lot]" in a literal translation.
If you really wanted to use あります above everything else (to emphasize the amount that remains), you could say カレーが少しあります (replacing すくない with すこし, which is... a really weird word in how it acts in Japanese sentences).