Extending Apps with Quick Actions 
You might wish to extend the scenario that was developed in the previous chapter to include additional functions. For example, you might be interested in extending the business logic so that status changes to individual instances of the Sales Order business object can be executed, without the end user having to switch to edit mode. In this case, the so-called quick actions come in to play
Quick actions are “one-click” actions with optional parameters. They are used for performing an action on each individual record without the need for the end user to switch to edit mode. For quick actions, no state needs to be kept on the client or back-end server. A quick action triggers the business logic in the back end that is immediately executed (in our case: written to the database. In a UI screen, the detail page (object page) might show the data as read-only and also offer quick actions without the need to switch to edit mode.
Action implementation and action control requires business logic that is implemented on the basis of the BOPF API. Therefore, quick actions are implemented as standard BOPF actions that are assigned to the related business object node. At runtime, a (quick) action can modify a node instance of the assigned business object or node instance of other associated business objects.
More on this: Understanding the Action API