An indefinite pronoun has no antecedent. We don’t know which noun is being replaced by the pronoun. That’s what makes them indefinite pronouns.
Here are three more indefinite pronouns: everyone, no one, someone
These indefinite pronouns are singular. They each take a singular verb when you use them in a sentence.
I hope everyone is hungry for dinner tonight.
I can’t believe that no one bought this beautiful dress.
I think someone is knocking at the door.
Use the pronouns everyone, no one, someone when you don’t know exactly who is being referred to.
▶Now you try it. Write a sentence using one of these indefinite pronouns. Be sure to use a singular verb with these singular pronouns.