Only readers not signed in under your account. I conclude this because I can visit my hubs on any given day, and some of my season-specific hubs will reflect "0" hits, even though I had gone on it to check polls. However, when others have read my material on my computer without me signing in first, their "hit" was reflected in the account. :)
For more specific tracking -- including geographic location of hits, register for a Google Analytics account. It's interesting to see people from across the globe reading your material! Registration is easily accessible, simply link to your "my account" on hubpages, then choose "affiliate settings" (center column of link menu). You'll see your choices for affiliate settings. "Analytics" is the bottom of first group of choices.