Roles are used to define which persons and/or teams who are responsible for the areas of the operation on the individual areas of the portfolio.
First you need to define the category of roles.
Follow the screenprint to setup the categories:
It is not necessarily the same persons who are responsible for the listed categories on the individual areas. This is why the responsible users should be added to the role of the area. Follow the screenprint to do this in any area:
After the setup of the role, you can make the user responsible of tasks. Read more about this here