Learn how to differentiate between countable and uncountable nouns. You can’t say one/two/three (etc.) + uncountable noun, and you cannot use a/an + uncountable noun.
Uncountable nouns have only one form and are typically used with “some”, “a lot of”, or “much”.
Examples:
air (singular), some/a lot of/much air (not “an air”, or “one air”, or “airs”)
anger (singular), some/a lot of/much anger (not “an anger”, or “one anger”, or “angers”)
Examples of words that signify the quantity of a noun:
A lot (of)
Many (countable nouns only)
Much
A little (bit of)
Some