Just like we see it on Audience->behavior->engagement->visit duration: 0-10seconds X people, 11-30s Y people, etc, but for a given page only. Not average time. Google analytics has the data since we can see that info for all the site... how to see it for a page?
The average time on page is readily available by going to:
Content -> Overview. The Avg. Time on page is displayed and from there you can drill down into individual pages to see the avg time on each individual page.