Take this scenario:

A kid called Jack. Local market. Cow. Beans.

Suppose the story read like this:

Jack' mother sent Jack to the market to sell a cow. Jack was supposed to come back with money so the family could eat. Instead, Jack bought some beans. Jack thought this was great because they were magic beans. Jack's mother thought otherwise. She was angry at Jack. Jack didn't care. Jack planted his beans in the garden.

The repetition of Jack above gets tiresome to read. Isn't there anything we can replace Jack with? Well, yes there is. Instead of repeating the noun Jack, it reads better if you replace it with a pronoun. Because Jack is a boy, the pronoun is he. Another masculine pronoun in English is him. The pronoun 'he' is called a subject pronoun while 'him' is called an object pronoun.

Jack's mother sent him to the market to sell a cow. He was supposed to come back with money so the family could eat.

Here is a list of some subject/object pronouns in English:

The Subject and Object refer to the verb. In English, subject pronouns usually go before the verb, while object pronouns go after the verb:

She loves him
He hates her
In the end? They kill them

There are also possessive pronouns:

Whose book is this? His.
Whose book is this? Hers.
Whose book is this? Mine.
Whose book is this? Theirs.
Whose book is this? Yours.

Somewhat confusingly, there are also possessive adjectives that look awfully like the possessive pronouns:

Whose book is this? His book.
Whose book is this? Her book.
Whose book is this? My book.
Whose book is this? Their book.
Whose book is this? Your book.

Pronouns can also be reflexive:

I myself
He himself
She herself
You yourself

(Basically, just add self to the subject pronoun.)

Pronouns have to agree in number. If a pronoun is singular, like nobody, then if you refer to that same 'nobody' later in the sentence, it too has to be singular. For example, take a look at these two sentences:

A) Nobody ever stubbed his toe on an adjective.

B) Nobody ever stubbed their toe on an adjective.

Which is correct? Answer, A. 'Nobody' and 'his' are both singular. We're talking about one person. So the pronouns agree. In B, 'Nobody' is paired with 'their'. You have a singular pronoun then a plural pronoun. One person has suddenly become more than one person.

This pronoun agreement thing is a big topic in Gender Studies. Take this sentence as an example:

No one stubs his toe on an adjective.

'No one' means no one person, either male or female. It's not gender-specific. Yet, we're matching it up to the masculine pronoun 'his'. You're implying that you haven't taken women into consideration, that the statement only applies to men.

We could say this instead:

No one stubs her toe on an adjective.

Except, the problem is the same - non-specific pronoun matched to a specific gender. This is the usual solution:

No one stubs his or her toe on an adjective.

Now we're matching 'his or her' to the non-specific 'no one'. We've solved the problem, yes, but the solution sounds clumsy and formal. No one speaks like that!

So, what have we learned? We've learned that pronouns stand in for nouns. They save you from being repetitive and sounding like you’re writing while incarcerated in an insane asylum.

And if you're quibbling about 'learned' and that it should be 'learnt' then I'm sorry Brits - it's learned now. Learnt is just about dead. You lost. Suck it up!