How to Use Pronouns
It may be a good idea to first list some common pronouns that are commonly used to replace nouns. They are: he, she, him, her, his, us, they, them, we, this, there, and that.
As mentioned, we use pronouns to avoid repeating the same word or words over and over again. Here is an example of where pronouns could have been used but weren't:
Bill likes dogs. Bill has a dog named Max. Bill takes Max for a walk every day. Bill feeds Max every day. Bill loves Max.
As you read, it may get annoying to see 'Bill' and 'Max' repeated over and over again. After Bill and Max's names have been used once, it is okay to use pronouns to replace their names; the reader will know who the pronoun is referring to. Here is an example of what it might look like if pronouns were used in the last example:
Bill likes dogs. He has a dog named Max. They go for a walk every day. Bill feeds him every day. Bill loves his dog.
As you can see, the pronouns gave the writing enough of a change so it didn't get repetitive, but it didn't change so much that you couldn't tell who was being talked about.
Here is another example where pronouns aren't used:
Bob and Sue are going to Hawaii. Bob and Sue can't wait to go to Hawaii. When Bob and Sue get to Hawaii, Bob and Sue are going to go to the beach.
As you can see, the words 'Bob', 'Sue', and 'Hawaii' are repeated a few times. But with some pronouns, we get:
Bob and Sue are going to Hawaii. They can't wait to get there. When they do, they are going to go to the beach.
In the last example, 'Bob', 'Sue', and 'Hawaii' are only used once. By swapping them out with pronouns, awkward repetition is avoided.