Unique visitors are exactly that, individual people visiting your site.
Non viewed traffic is search engines viewing your site, not people.
Hits are all the pages viewed, so if one person looks at ten pages on your site then that will generate ten hits, if they look at the same page twice then it will count that as two seperate hits, pages are the amount of pages viewed, if the same Person views the same page twice or more, that will count as one page view.
The important numbers are the unique visitors and where they are leaving yor site (bounce rate) you can check where visitors are entering and leaving your site if you look at the most viewed URLs (pages).
Awstats is quite good