A pronoun referring to something near the listener or something related to the listener; 'that' or 'it'.
それ、ちょっと貸してもらえますか？
Could I borrow that for a moment?
それはどういう意味ですか？
What does that mean?
それを見せてください。
Please show me that.
Refers to a point in time or that particular case (then; at that point).
彼は学生だった。それは十年前の話だ。
He was a student. That was a story from ten years ago.
それでは、会議を始めます。
Well then, we'll begin the meeting.
An archaic usage meaning 'there' (near the listener), equivalent to 'そこ' in modern Japanese.
（書き言葉・古語）其れには古い井戸があった。
(Written/archaic) There was an old well there.
An archaic second-person pronoun meaning 'you' (rare in modern usage).
（古語）其れ、何を為すか。
(Archaic) You—what are you doing?