Hi Pedro,
Outsystems has a BPT (Business Process Technology) component that allows you to define workflows to assist in business processes. These processes can be automatically initiated based on an event.
The 'Expose Process Events' option that you see for an Entity allows BPT to use an action on that Entity to start an instance of a process. The action in this case is 'create record'.
Ticking the box effectively means that Outsystems will include that Entity in a list so you can pick what starts a new workflow process.
If you go to the Processes tab and create a Process, you're looking for that Entity in the 'Launch On' property.
Thanks,
David