Departments are a great way to categorize your jobs. You can assign jobs to belong to a department.
You can create a department by clicking the "New" button in the departments settings or adding it when creating a job posting. This will be the tag to categorize and filter your Jobs on your Careers Site.
When you create your job posting, you can add the category to the job.
Once you set up a department, you can edit and delete them and see how many jobs are associated per department.