Proper Noun : Proper noun is the name of a particular person , thing or place.
Example : Names like Shravani, Vishal, Somendra etc.
Places like India, Guwahati, Orissa etc
Common Noun : A common noun is a name shared by every person or thing of the same class. It does not refer to any particular person or thing.
Example : Teacher, Doctors, Students etc.
Pronoun : Is a word used in place of a noun.
Example : Somendra is a good boy. He is the class topper.
Here, he is a pronoun used in place of Somendra (Proper Noun).