The server status widget was added in MineSync 3.2. It allows you to display your server status as a widget, showing the server IP, online/offline status, and the current logged in players (out of the maximum players). Players can also copy the IP address by clicking on it.
To add the widget, go to your admin panel in XenForo, visit Appearance -> Widgets and click "Add widget". Add a widget using the "MineSync: Server status" definition. Here you can set the options as desired, there are comments below the three options relating to the server information needed to run a query, server name, server address and server port, to help you fill out these values. You can only add one server IP per widget, but can add an unlimited amount of widgets.
By default, server status information is cached and updated each minute. You can disable caching so it instead updates the status each time a page is loaded (with a widget on it) by toggling "Disable server status cache" in your admin panel -> Options -> [n] MineSync -> Disable server status cache.