Role is a way of participation by a party (person or organization), place or thing. Many times a person or organization are eligible to play the same role (for example, owner) within a problem domain that we are working in.
So we model the role-player (a party, place, or thing) as well as the role (the "hat" that the party, place, or thing is wearing). The role player captures core attributes and behaviors that apply no matter what combination of hats it might be wearing. For person, that often includes attributes like legal name and date of birth. It also includes methods that enforce business rules across the collection of roles being played, for example, a method "authorized for" that interacts with each role and applies rules across that collection of roles to determine if it is authorized to take a given action.
Party, person, and organization roles are the norm. Occasionally you'll find place and thing roles too (for example, a product and its two roles, "product in a sales process" and "product in use").