From looking at your image, I would interpret the following:
First, to answer your question, the arrow should only be pointing to the works_in3 table. If it was pointing to the department table it should go around works.
Employee table: one to one relationship between ssn - name - lot (not sure what this field really is.) Key field seems to be ssn.
Works-in3 - one to many relationship between employee identifier (likely ssn) and since (guessing there is a department name or number in there somewhere.)
Locations: one to many relationship between works-in3 (many locations) and location table (one address, one capacity on each location.) Address is key field(?) - I question that because address isn't a good key, I'm guessing there is some sort of location identifier.
Department: one to many relationship between department (did seems to be key field) and works-in3.
Since only Employees -> works_in3 has an arrow, then I believe that there is a one to many relationship between employee (1 employee) and works_in3 (many potential entries possible for each employee depending on job(s) held.)
So, for each employee (always only 1 employee record) there is a current works_in3 record with since as the identifier. The other data in the record is from department (details) and location (details.) Each employee can have many works_in3 records showing work history.