Enough can be used as a quantifier when it is placed before any noun, to indicate the quantity required or necessary. It can be used in both affirmative and negative sentences.
- There is enough bread for lunch.
- She has enough money.
- There are not enough apples for all of us.
- I don't have enough sugar to make a cake.
The word enough can also be an adverb of degree, in which case it is not placed before a noun.