The Job settings is an area where you can configure the categories to be displayed in the Jobs Module. Categories consist of (for example) Jobs, Consultants, Mechanics. Categories can be customised to be any entity that fits your business - create as many resource categories as desired.
You may not want to display (for example) the Staff and Vehicle categories in the Jobs module, so you can deselect them from showing, by configuring them in the Job Settings area.