‘No’ is usually used to mean something like “not any” or “not a/an”, and usually refers to a noun. It is commonly used in the following situations:
Answering a yes or no question
E.g. Did you finish your homework? No, I didn’t finish my homework.
Using ‘no’ for nouns without an article
E.g. Sarah has no idea where her phone is.
E.g. This is no time for fighting!
E.g. The book has no information.
Adjectives preceding a noun without an article
E.g. I checked the website, but there are no red dresses.
E.g. There were no late trains today.
E.g. The school has no bad teachers.
Before verbal nouns (ending in -ing)
E.g. No smoking.
E.g. No playing in the street!
E.g. No texting during school!
Not is used to express negation in other ways:
For verbs, to show the opposite of an action
E.g. I do not like this colour.
E.g. He is not cooking dinner tonight.
E.g. You cannot go to Jack’s house.
Also for adverbs which are describing a verb
E.g. I don’t like that actor.
Why not? [Why don’t you like that actor?]
E.g. The car is not very fast.
E.g. Not surprisingly, the hotel was very nice.
Nouns with an article
This also includes nouns with an article, which are preceded by an adjective, and adjectives on their own.
E.g. I liked the pink dress, but not the red one.
E.g. He is not a teacher; he is a student.
E.g. Josh is not friendly.