A voltage graph is like a picture that shows how much electricity is flowing through something over time. It's kind of like a roller coaster ride at an amusement park. When you look at a roller coaster ride, you can see how the tracks go up and down, just like the voltage graph shows how the electricity goes up and down.
Imagine that you have a toy car that needs a battery to work. The battery has some energy stored in it, just like a roller coaster has a lot of potential energy at the very top of the ride. When you put the battery into the toy car, you create a circuit that allows electricity to flow from the battery, through the car, and back to the battery again. Just like when you release a roller coaster at the top of its climb, the energy from the battery is "released" and starts to flow through the wires.
Now, let's imagine that you're measuring the flow of electricity in the toy car with a special device called a voltmeter. A voltmeter is a tool that measures the electrical potential difference between two points. In this case, the voltmeter would tell you how many volts (units of energy) are flowing through the car's circuit.
As the toy car moves, the amount of electricity flowing through the circuit will change. When the car is moving slowly, the voltage might be low (just like how the roller coaster doesn't have much potential energy when it's moving slowly). But when the car speeds up, the voltage will increase (just like how the roller coaster gains more potential energy as it goes faster).
If you were to draw a graph of the voltage over time, it would look like a bunch of ups and downs, kind of like a roller coaster ride. The graph would show you when the voltage was high and when it was low, and you could use that information to figure out how the toy car was moving.