How to interpret ternary relationship?
This looks to me that an employee works in at department at a location since a point in time.  I don’t recognise the diagram type as an ERD so I can’t tell what type of relationships they are but I expect that they are one to many. i.e. the works_in3 table is a link table to facilitate a many to many relationship of employee and department. As for location I expect this is where the employee worked in this department, again representing a many to many relationships, as one location could house many employees performing many roles for departments. But that’s just my opinion.