Can anyone help in understand how Use Score works in HR Help Desk Assignment Rules?

Summary:
How Use Score can be used to differentiate HR Help Desk queues?

Content (please ensure you mask any confidential information):

We have configured different HR Help Desk queues like Absence, Benefits, Compensation & Salary, etc. and we have configured respective Service Assignment rule sets with the names Absence, Benefits, Compensation & Salary, etc. We have given conditions with the related keywords to the respective Queues.

We have created another rule titled Public Safety with the condition that Primary Employee Contact should be of specific departments. So whatever Help Desk Requests are created by the employees in those departments, it should be assigned to the Public Safety queue.