Website Name:W3Schools
Website Purpose: Learning to Code
Yes it does.
I clicked on the link for C, this page validates as well.
The home page had 5 warnings and 31 errors. Second page C had 5 warnings and 18 errors.
I would give the site a 5. I don't know a ton about site design but I know personally I do not like when sites have a bunch of adds all over on each page. Beyond that it is pretty basic and not really all that visually appealing.
For this I rate it 7. As far as navigating the site it is straight forward and easy. If you want to do something on HTML you click the link and then there are quite a few other links relating to different aspects of HTML itself. Same goes for each of the other coding languages.
I would think so, its there to teach you coding and it looks like there are lots of resources to meet that end.