To demonstrate is to show something. Demonstrative pronouns show or point to objects or people. These pronouns can indicate items in space or time, and they can be either singular or plural.
Demonstrative Pronouns:
Close to Speaker Far from Speaker
Singular This That
Plural These Those
This and that refer to singular objects or people.
Example: This is an expensive watch.
That is a very beautiful dress.
These and those refer to plural objects or people.
Examples: These are my places of interest.
Those are the sweetest mangoes I ever had.
It is never correct to combine 'this' with 'here' or 'those' with 'there'. Here and there are already understood in the demonstrative pronouns.
This here is my favorite movie. (Incorrect)
This is my favorite movie. (Correct)
That there is the best play ever. (Incorrect)
That is the best play ever. (Correct)