زیاد

In a sentence

• من زیاد کتاب می‌خوانم.

  I read a lot of books.

  Here, 'زیاد' is used as an adverb to indicate the frequency or quantity of the action (reading books).

• غذا در این رستوران زیاد است.

  There is a lot of food in this restaurant.

  In this context, 'زیاد' is used as an adjective to describe the abundance of food.

• او زیاد درس نمی‌خواند.

  He doesn't study a lot.

  Here, 'زیاد' is again used as an adverb, but in a negative form, to show the lack of intensity of the action (studying).