Within the domain of web traffic analysis there are two stats that are often confused: exit rate, and bounce rate.
Both involve people leaving your website, so you want both to be as low as possible. Here’s how they differ:
Exit Rate pertains to pageviews, and simply means that for all views to a given page, the exit rate is the % where it was the last page of the session.
Bounce Rate is just the number of sessions that start and end with only one page.
So the bounce rate is much more important to keep down, to my understanding, as it means people are not exploring other parts of your site when they arrive.
Hope this helps.