How would you use that as a pronoun?

The Word 'that' is a pronoun, an adjective, an adverb and a conjunction.

The pronoun 'that' is a demonstrative pronoun and a relative pronoun.

A demonstrative pronoun takes the place of a noun, indicating near or far in place or time.

They are: this, that, these, those.

A relative pronoun introduces a relative clause, which "relates" to the its antecedent, providing additional information about the antecedent without starting another sentence.

They are: who, whom, whose, which, that.

Examples:

He brought his mother flowers. I like that. (demonstrative pronoun)

The flowers that he brought were roses. (relative pronoun)

More examples for 'that':

He brought his mother flowers. I like thatgesture. (adjective)

I didn't realize he was that extravagant. (adverb)

His mother was delighted that he was so thoughtful. (conjunction)