A website shows some text, pictures to the visitor who wants to see or to know about something. So basically what a website does is to show information to some visitors.
A website is like a book. An online version of a book that could be much more complicated than a book. You could give the user many chances to reach what they want by some clicks where in a book it is not possible.
A website is some pages on the internet. These pages could be related to each other in other words they could be linked together.
Each of these pages have text and maybe pictures. That is what a computer could show to the user text and pictures. But in some cases with programming languages they give life to pictures and texts. You have seen movies on the websites. Those are combinations of some many pictures that are being changed fast.
So websites are great, they could show information to users easily.