これ/それ/あれ — "this, that, that over there"
これ/それ/あれ は N です
These are demonstrative pronouns that work like nouns. これ points at something near the speaker, それ at something near the listener, and あれ at something far from both.
Examples
これは 辞書です。
This is a dictionary.
それはボールペンですか。
Is that a pen?
あれは 私のかばんです。
That over there is my bag.