The word ‘we’ is classified as a pronoun, specifically a personal pronoun used to refer to a group that includes the speaker. It is neither a common noun nor a proper noun.
To clarify, common nouns refer to general items, places, or concepts (like ‘city’ or ‘dog’), while proper nouns name specific people, places, or organizations (like ‘New York’ or ‘Fido’). Since ‘we’ does not fit into either category, it is best understood as a pronoun used for communication.