What does the data mean?

I had wrote an automation,it can work,when file changed “deleted ,created,moved”,it send an email.

- id: '123'
  alias: "file changed"
  trigger:
    - platform: event
      event_type: folder_watcher
  condition:
    - "{{ trigger.event.data.event_type in ['deleted', 'moved', 'created'] }}"
  action:
    - service: notify.send_email
    data:
      title:  "{{ trigger.event.data.event_type in ['deleted', 'moved', 'created'] }}"
      message: " {{ trigger.event.data.file }} in {{ trigger.event.data.folder }}"
      data:
        file: "{{ trigger.event.data.path }}"

The email only contains two main elements:tile and body(message).
What does the data mean?

      data:
        file: "{{ trigger.event.data.path }}

I’m not sure what you mean - if you wrote the automation, why did you put that line in?