Okay kiddo, have you ever been in a car and noticed how the driver can change how fast the car goes? They can use the gas pedal to accelerate or slow down by using the brakes, right?
Well, it's kind of like that when it comes to a computer's speed. You have something called a fan inside your computer that helps to keep it cool while it runs. A program called SpeedFan lets you control how fast that fan spins.
So, if your computer is working really hard and getting a bit warm, you can use SpeedFan to make the fan go faster and cool it down. Or if you don't need your computer to work as hard and want it to be quieter, you can use SpeedFan to make the fan slow down.
It's like having your very own controller to make your computer run faster or slower, just like a gas pedal in a car!