This report lets you see how much time people spend on your site, in increments of seconds, and how many pages they view.
Single-page sessions are assigned to the 0-10 session-duration and < 1 page-depth categories. Google Analytics determines session duration by tracking the elapsed time between pageviews. The last page of a session is not recorded since there is no subsequent pageview.
Depending on the nature of your site, your target duration for a session will vary. For example, if you have a blog or news site, you're probably hoping users spend some time there to carefully read through the content. On the other hand, if the purpose of your site is to let people purchase the items in their shopping carts and they're spending a lot of time there, you might conclude that your check-out process is unnecessarily complicated.
As with session duration, your goals for page depth can vary depending on the nature of your site. If you're running the website for a college, you want users to look at the pages that give a background of the school, describe the different departments and faculties, highlight sports programs and social activities, along with pages that provide information about the submissions process. If the purpose of your site is to provide contact information for government agencies in your county, you may want your users to have to view only one or two pages before they find the information they need.