This is the 928th most frequent Polish word.
niewiele
"Not much" or "little."
Here, 'niewiele' is used with an uncountable noun 'pieniędzy' to indicate a small amount.
Mam niewiele pieniędzy na zakupy.
I have little money for shopping.
In this sentence, 'niewiele' defines a small specific number in relation to 'dni' (days).
W niewiele dni po jej powrocie, wyjechała ponownie.
A few days after her return, she left again.
Here, 'niewiele' specifies a small quantity related to 'osób' (people) emphasizing the limited count.