There isn't an old school counter that you can add to the website. You can now use google analytics.
After you setup a google analytics account you will go into you site settings and paste in your analytics account number. Ignore the part about pasting code onto every page, it's not necessary when using analytics with a google site.
from here you can get all kinds of stats on you website. **note** it takes a few days once you have put your account number in sites before you will start seeing stats at google analytics.