Is a last name a pronoun?

No, a name (first or last) is a noun, a Word for a person. The name of a person is a proper noun.

A pronoun is a Word that takes the place of a noun in a sentence.

Example:

My new neighbor is Mr. Perez. I believe that hecomes from California. (the pronoun 'he' takes the places of the proper noun 'Mr. Perez' in the second sentence)