Use нљсколько 'some, a few' with count nouns, i.e. nouns that refer to countable objects, like glasses, pens, books, etc.
  нљсколько стакђнов a few glasses  
Use немнћго 'some, a little bit' with mass nouns, i.e. nouns that refer to things that you don't normally use numbers with, like tea, cheese, caviar, etc.
  немнћго икрІ a little caviar  
Many nouns that are countable in English have uncountable equivalents in Russian:
  немнћго картћшки (Gen. Sg.) a few potatoes  
  немнћго лџка (Gen. Sg.) a few onions