A truck stop is a small area near or on a major road. They usually include a gas station, a rest stop, a scale, and a small diner or convenience store as detail and some also feature service shops. Truck stops can be found in both Euro Truck Simulator 2 and American Truck Simulator.
If you own the New Mexico DLC, you can get Truck Stop Tour as an achievement by visiting all the truck stops in New Mexico.
In the 1.38 update, all truck stops got a major upgrade and dual side fueling was implemented. Trucks can now refuel at both sides.