iWeb and PS3

why can't PS3 show websites created by iWeb?

Presumably its specialized browser cannot handle the iweb code. Best to ask whoever is responsible for the PS3's software.

but isn't html the code of iWeb?

Not all browsers can read all html as intended by the page author. If you wanted to make a page that was guaranteed to be displayed correctly by the PS 3, you would need to find some info about what that browser requires and create your page accordingly -- probably with some app other than iWeb, which does not allow you to edit its html.