What is a pronoun?
A pronoun is word which is used to refer to something when a noun is not used.  Examples of pronoun words are he, she, it, myself, herself, and himself.  In a sentence you will see the pronoun used like this "John went the store to buy himself and apple and crackers."  In this context John is a proper noun and the pronoun is himself which refers to John.  Another way to consider a pronoun is that it is a less explicit or indirect reference to something.