pronoun

A pronoun is used to substitute for an implied noun or an antecedent—that is, a noun, noun phrase, clause, or other pronoun that has come before. According to conventional pronoun usage rules, this part of speech has two main purposes.

1.  Pronouns reduce repetition—for example:

Friends of Susan Powell told the Salt Lake Tribune she was afraid her husband Joshua Powell would kidnap her sons if she divorced him.

This is more graceful than the alternative,

Friends of Susan Powell told the Salt Lake Tribune Susan Powell was afraid Susan Powell’s husband Joshua Powell would kidnap Susan Powell’s sons if Susan Powell divorced Joshua Powell.

2.  Pronouns can stand in for implied nouns. Here, the “she” and “he” in the second sentence recall nouns introduced in the first sentence:

Betty Emmerson of Yakima has known Broderson since his youth. She said he’s grown into a wonderful and caring man.

In other cases, the implied noun may be entirely absent—for example:

After a bumper set of encores and nearly 40 songs, McCartney sadly has to go. It really doesn’t get any better than this.

The it in the second sentence doesn’t recall a noun from earlier, but we know the author means something like, “[The concert-going experience] doesn’t get any better than this.”