GROUP›used after a verb or preposition to refer to a group of people, animals, or things that have already been talked about: I'm looking for my keys - have you seen them?
HIM/HER›used after a verb or preposition to refer to a person when you want to avoid saying 'him' or 'her' or when you do not know if the person is male or female: When each passenger arrives we ask them to fill in a form.