Okay, so let's imagine that you have a toy car. The car has a body, wheels, and a motor that makes it go. The body of the toy car is like the coachwork of a real car.
Now, coachwork is the part of a car that makes it look pretty and unique. It's kind of like the clothes you wear to make you look nice and different from other people.
Sometimes, car makers make the coachwork themselves. Other times, they hire special people called coachbuilders. Coachbuilders are like fashion designers for cars. They create the coachwork based on what the car owner wants.
So, let's say you have a toy car with a plain body. You could ask a coachbuilder to make a special body for your toy car. They might add cool features like wings or a spoiler. Just like how you might ask someone to make a special outfit for you with fun accessories.
In real life, cars with coachwork are usually very expensive and fancy. They're often custom-made and unique. But, just like with your toy car, it's the coachwork that makes them stand out and look special.