WP Job Manager adds an ’employer’ role to your site.
By default, if a user registers on your site while posting a job, they will be assigned the ’employer’ role, but you can change this to any role in Job Listings > Settings > Job Submission
The ’employer’ role doesn’t give the user any special capabilities by default. It is mainly used by 3rd party themes/plugins, and you can also use it to restrict certain views to the ’employer’ role, as described here.
If you need to customize the capabilities of the ’employer’ role, you’ll need to use a plugin such as User Role Editor