You don’t want to focus only on the movement of your visitor within your domain. You want to learn where do they go directly from your website. And Outlinks report can help you gain a lot of insight into this. It displays data about all the links located on your website that take visitors away from your website to another domain. So if there is a link to another site (even an ad banner or a social media button), the Outlinks report will display the number of times your visitors clicked on it.
To put it simply: Piwik PRO can track all URLs that are not the same domain as the website being tracked.