The Exit Page is the last page accessed during a visit.
Matomo (Piwik) reports the top Exit Page URLs, the number of Exits, Unique Pageviews and Exit Rate. Exit rate (sometimes called “Page Exit Ratio”) is the number of Exits from a page divided by total number of Page views of that page.
You can see all exit pages in the report at Behaviour > Exit pages.
See also our glossary of analytics terms.