In the English language, there are four words which can be used as demonstrative determiners, better known as demonstrative adjectives or demonstrative pronouns depending on their purpose in a sentence. The four most common demonstrative adjectives in English are this, that, these and those.
Let’s divide this into the following criteria:
#1)This and that refer to singular nouns, while these and those refer to plural nouns:
This/that ---- > singular
These/those ---- > plural
#2) The words "this" and "that" etc. can function as both adjectives and pronouns.
This book is mine. (adjective)
This (one) is mine. (pronoun)
That book is yours.(adjective)
That (one) is yours. (pronoun)
#3) This/These are used to talk about people, animals or things which are near us.
That/those are used to talk about people, animals or things are far away from us.
This is my hat (near us)
That is my car (far away from us)
These are my shoes (near)
Those are balloons (far)
4) Notice that when we ask What’s this?/ What are these?/ What’s that?/ What are those?
we answer It is (It’s) or They are (They’re)
e.g. What’s this/that? ---> It’s a cat. NOT: This/That is a cat
What are these/those? ---> They’re shoes. NOT: These/those are shoes.
I hope this HELPS you.