We use a few and a little to mean "not very much" or "not very many". Whether you use a few or a little depends on what type of noun you are describing.
For example, "A few people came to the party." We use a few with plural, countable nouns.
"There's a little coffee left, if you would like some." We use a little with uncountable nouns.
We can also use few and little (without "a") for a more negative meaning. For example, "there's little point in calling" (= there's not much point calling).
"Few people understand" (not many people understand), compared to "a few people understand" (some people understand).
In spoken English, we can also say not many, or only a few to mean "few" and "only a little" or "not much" to mean "little".
When we make comparisons, we use fewer for plural nouns and less for uncountable nouns.
For example, "There are fewer people here than last year" or "he drinks less coffee than I do".
For example, "There are fewer people here than last year" or "he drinks less coffee than I do".