Here's why:
* Pronouns are words that stand in for nouns. They are used to avoid repetition and make writing more concise.
* Nouns are words that name people, places, things, or ideas.
Example:
* Sentence: The cat sat on the mat. It was a fluffy cat.
* Pronoun: "It" replaces the noun "cat" in the second sentence.
Let me know if you have any other questions!