Role actions are spells and weaponskills that are assigned to all the classes within a role (Tank, Melee DPS, Ranged DPS, Healer) rather than a specific class. Role actions are learned in the same manner as class actions - via leveling - but only need to be learned once to be able to use them with all participating classes within a role.
They can be found in the Action List under Character in the main menu. Selecting it will display the role actions a player has learned. The number of role actions that can be assigned to the current class (from 1 to a maximum of 10) is determined by the level of that class. To assign a role action to a class, simply check the box next to the action's name. Boxes cannot be unchecked if that action is currently on cooldown. The role actions currently selected will appear at the bottom of the Action List. The icons of those actions can be dragged and dropped into the hotbars.