Explanation
Overview of Events
Oracle Cloud Infrastructure Events enables you to create automation based on the state changes of resources throughout your tenancy. Use Events to allow your development teams to automatically respond when a resource changes its state.
Event Rules must also specify an action to trigger when the filter finds a matching event. Actions are responses you define for event matches. You set up select Oracle Cloud Infrastructure services that the Events service has established as actions. The resources for these services act as destinations for matching events.
When the filter in the rule finds a match, the Events service delivers the matching event to one or more of the destinations you identified in the rule. The destination service that receives the event then processes the event in whatever manner you defined. This delivery provides the automation in your environment.
You can only deliver events to certain Oracle Cloud Infrastructure services with a rule. Use the following services to create actions:
Notifications
Streaming
Functions

References:
https://docs.cloud.oracle.com/en-us/iaas/Content/Events/Concepts/eventsoverview.htm