I am confused pronoun and noun

everything is noun, noun is a naming word, like--rohan, delhi, stone, Rice, field, gold anything we use pronoun instead of noun Rohan is going to office and he will be free around 6pm in this sentence we use He instead of Rohan. Neha is a good dancer. she is also a good singer.

noun is nothing but names of a person, place, thing,etc.. pronoun is a word which we use instead of noun. ex.Ramu is a clever boy, everybody likes him. in this sentence "Ramu" is noun because it is a name of a person."him"is a pronoun as we use it instead of Ramu.