The position is the title of the Job Publication. The position is what an applicant sees as the title of the Job Advertisement.

This title initially corresponds to the main title of the Job Opening when you create a Job Publication, but it can be customized. 

Customization is useful, for example, if you create Job Publications in multiple languages.

In the application search, application overview and job advertisement overview, you can filter by Position/Main Title. With this filter you can search with parts of a title. All results will be displayed which contain this combination of letters.

It is not possible to create a report that contains the Position field. Since the applications are on a Job Opening - not on a job publication.