Exit rate is the percentage of people who left your site from that page. Exits may have viewed more than one page in a session. That means they may not have landed on that page, but simply found their way to it through site navigation.
Like bounce rates, high exit rates can often reveal problem areas on your site. But the same type of caution needs to be applied. If you have a paginated article – say four pages – and the exit rate on the last page is high, is that really a bad thing? They’ve reached the end of the article. It may be natural for them to leave at that point.
Of course, you’ll want to try different UX treatments for surfacing related articles or encourage social interactions to reduce the exit rate, but that it was high to begin with shouldn’t create panic.
Exit rate should be looked at within a relative navigation context. Pages that should naturally create further click, but don’t, are ripe for optimization.