What is the pronoun in this sentence:

"The girl took her cat outside"

A pronoun is a word used in place of a noun, so "her" would be the pronoun.

First, you have to understand what a pronoun is: A pronoun is any word that takes the place of another noun/object in the sentence. The noun can be proper or improper it doesn't really matter.

So, "The girl" is our noun, and "her" is a substitute for "The girl", so "her" is the proper noun.