When we state exactly or in detail the nouns that we refer to, we generally use the words:

• This

• That

• These

• Those

They are demonstrative pronouns. They are used to point to persons, things, or places.

This is used to point to a person, a thing, or a place which is near the speaker.

Example:
This is my pen.

These is used to point to two or more persons, things, or places which are near the speaker.

Example:
These are my pens.

That is used to point to a person, a thing, or a place which is far from the speaker.

Example:
That is a new house.

Those is used to point to two or more persons, things, or places which are far from the speaker.

Example:
Those are the new houses.

This and that are used for singular nouns.

These and those are used for plural nouns.

This and these are used to indicate persons, things, or places close to the speaker.

That and those are used to indicate persons, things, or places far from the speaker.