An indefinite pronoun refers to a non-specific person or thing. The most common indefinite pronouns are: some, somebody, anything, anyone, everything, everybody, everyone, nobody, one, none, all, any, each, several, few, many.
E.g. Somebody must have seen the officer leave. He wants some water. Everyone goes home at 6 o'clock. Is she any better today? All were present at the meeting. I know none of them. How many do you want?