Okay kiddo, imagine you have a piano but it's not real. It's on your computer or phone, and you can play it using your mouse or typing on your keyboard. This is called a virtual piano.
Now, instead of actually hitting the piano keys with your fingers, you click on the images of the keys on your screen. You can move your mouse up and down to hit different notes just like how you would move your fingers on a real piano.
Some virtual pianos even let you record the music you make, so you can listen to it again later or share it with your friends.
Now go ahead, give it a try and create a beautiful melody!