Here's why:
* Pronouns are words that replace nouns or noun phrases. This avoids repetition and makes writing more concise.
Examples:
* He went to the store. ("He" replaces the noun "John")
* They are going to the park. ("They" replaces the noun phrase "The children")
* It is raining. ("It" replaces the noun phrase "The weather")
Let me know if you have any other questions!