What is a Pronoun?

pronoun (noun): a word that takes the place of or represents a noun

Pronouns are small words that take the place of a noun. We can use a pronoun instead of a noun. Pronouns are words like: he, you, ours, themselves, some, each... If we didn't have pronouns, we would have to repeat a lot of nouns. We would have to say things like:

• Do you like the manager? I don't like the manager. The manager's not friendly.

With pronouns, we can say:

• Do you like the manager? I don't like him. He's not friendly.

A pronoun is a small word with a big job. In fact, a pronoun can take the place of an entire noun phrase. In this way, pronouns help us use fewer words and avoid repetition.
In the sentence "Please give this letter to Rosemary", we can replace "this letter" with "it" and "Rosemary" with "her", as you see below:

Please give	this letter	to	Rosemary.
Please give	it	to	her.

In a conversation, the speakers normally use pronouns to address each other: I speak to you. You speak to me. When we talk about John, we don't keep repeating John's name. We say he or him. If we talk about a thing, we can use the pronoun it.
A pronoun represents the person or thing that we are talking about (as long as we know which person or thing we are talking about). We don't usually start a discourse with a pronoun. We start with a noun and then move on to use a pronoun to avoid repeating the noun.
By "noun", we really mean: noun (food), name (Tara), gerund (swimming), noun phrase (twelve red roses). We can replace even a long noun phrase such as "the car that we saw crashing into the bus" with the simple pronoun "it".
Here are some examples of noun phrases and the pronouns that could replace them:

noun (phrase)	pronoun
the car	it
Anthony	he
the big woman with black hair	she
swimming	it
learning English	it
almost all French people	they
my wife and I	we

pro + noun = "on behalf of" + noun

There are different types of pronoun, but they all have the same job - to represent a noun (phrase).