The word everyone is a pronoun.
Pronouns are words that take the place of a noun or noun phrase. In the case of everyone, it refers to all people in a group and serves as a substitute for more specific nouns. For example, instead of saying ‘all the students,’ one can simply say ‘everyone’ to include all individuals in that group.
Because everyone functions as a substitute for a noun, it falls under the category of pronouns, making it a part of speech used to denote people in a general sense, without naming them individually.