Portable-VirtualBox is like a magic box that you can carry around wherever you go. Inside this magic box, there is a special kind of computer that you can use without actually having to buy or carry a physical computer with you all the time. This computer is called a virtual machine.
When you open the magic box, you can see this special computer running on your own computer screen. You can use it just like a normal computer, do whatever you want on it, and then close the magic box when you're done.
The amazing thing about this magic box is that you can use it on any computer that you want, whether it's your own computer, a friend's computer or even a public computer like the ones you find in libraries or internet cafes. You don't have to worry about installing anything on the computer you're using because all the software and files you need are already inside the magic box.
Portable-VirtualBox is a special kind of magic box that you can put on a USB drive or any other portable device, and carry around with you wherever you go. This means that in addition to not having to carry a physical computer, you don't even have to carry a bulky laptop around because you can just use the magic box on any computer you want.
So in short, Portable-VirtualBox is like carrying a whole computer in a small box, that you can use on any computer you want. Pretty cool, huh?