Count nouns name things we can count:
apple - 1 apple, 2 apples, many apples
girl - 1 girl, 4 girls, many girls
Count nouns have 2 forms - singular (יחיד) and plural (רבים).
We put "a" or "an" before count nouns in singular form (a/an=one)
an - before nouns that begin with a vowel (אות נקוד)
an apple, an egg, an igloo, an ostrich, an umbrella
a - before nouns that begin with a consonant (אות עיצור)
a box, a flower, a girl, a skateboard
Non-count nouns name things we can not count:
milk, tea, water, juice, coffee...
flour, rice, sugar, salt ....
snow, rain, weather, air ....
We can put the word "some (כמה, קצת) before non-count nouns:
some water, some rain, some butter