DEMONSTRATIVES - this, that, these, those

This/that/these/those show the relative distance between the speaker and a noun.

This refers to something near to the speaker, that to something further away. These is the plural of "this", and "those" is the plural of "that".

Sometimes demonstratives are pronouns, for example:
- "This is my Mom." Mom is near to the speaker
- "These are my books." The books are near the speaker.
- "I don't like that." He doesn't like something that is further away.

Sometimes demonstratives can also be adjectives, for example:
- "That man is a doctor."
- "I like those jackets."
- "I don't like that movie."


http://www.1-language.com/englishcourse/unit12_grammar.htm