Road tax is a fee you pay to the government for the privilege of driving your car on public roads. It's like paying to enter a theme park, but instead of getting on rides, you get to drive your car.
The money from road tax is used to help pay for building and maintaining the roads and keeping them safe for everyone who uses them. This includes repairing potholes, making sure road signs and traffic lights work properly, and even paying the people who patrol the roads and make sure everyone is driving safely.
So, just like how you have to pay for a ticket to see a movie or go to the zoo, you have to pay your road tax to be allowed to drive on public roads. And if you don't pay your road tax, you might get in trouble with the government, just like if you sneak into a movie without buying a ticket.