Tutorial NPCs exist to help you. They provide kind explanation about your environment. They can also be hired for your own purpose in order to provide help around your faction starting location. You can find them in each Civic Centre used as starting location for a specific race and the city containing it. Tutorial NPCs usually appear in yellow on your scanners.
Tutorial NPCs are spawned automatically. If one of them goes missing (killed, moved out of the city, or if a new starting location appears), new NPCs will appear after up to 24h.
All Tutorial NPCs have the same class skill and can be hired for free. If no hiring location is displayed then it means that kind of NPC is automatically spawned at locations selected by the Administration and therefore is not available to hire.