What does vetted role mean?
In order for a Drupal contributed module to be eligible to be tagged as a security monitored project, one or more of the maintainers have to be 'vetted'.
Here is the main Drupal security policy on this.  See the &quot;Which Projects are covered&quot; section.  There is a link in this to the process of becoming 'vetted'.
Basically, you submit a Drupal.org project to a queue.  Eventually, security community members will review it for use of best security practices, code quality, and some other stuff.  If approved, the maintainer becomes 'vetted'.  Unfortunately, this process can take a long time to happen.
Once you have a project approved and are 'vetted', any other projects you maintain can be labeled as covered by the security community.