GA definition: The total number of pages viewed. Repeated views of a single page are counted.
A pageview is simply a viewed page.
GA definition: The number of visits during which one or more of these pages was viewed.
A unique pageview aggregates pageviews that are generated by the same user during the same half-hour session.
Average time on page
GA definition: The average amount of time visitors spent viewing a page or set of pages.
Bounce Rate is the percentage of single-page visits (i.e. visits in which the person left your site from the entrance page without interacting with the page).
A high bounce rate generally indicates that site entrance pages aren't relevant to your visitors.
GA definition: %Exit is (number of exits) / (number of pageviews) for the page or set of pages. It indicates how often users exit from that page or set of pages when they view the page(s).