Question

What is a pronoun? Is "my" a pronoun? The way it is used in the sentence below: My teacher said my math is canceled today.

Answer 1

Yes, the word "my" is a pronoun . Instead of noun, we use a pronoun. It is also a pronoun but it is called possessive adjective .

Explanation:

My, your, his, her, its, our, and their are possessive adjectives, words that take the place of possessive nouns.
The possessive adjective "my" takes the place of the possessive form of the noun (name) for the person speaking.

We must know if we use two nouns one by one
like other teacher, here other is an adjective though other could be a noun too by another context..
So, you can't write others teachers, as an adjective can not take a plural form. shoes store, notebooks paper etc.

This rule noun==pronoun, same.
so pronoun my/his/our/their/your etc can not be nouns too, logic says.