The text discusses the role of Couchbase Sync Gateway in the Couchbase Mobile stack, which facilitates secure data synchronization for offline-first mobile apps using a websockets-based replication protocol. It highlights a tutorial that extends the capabilities of Couchbase Lite clients by incorporating data synchronization through the Sync Gateway, emphasizing the importance of offline data storage and cloud synchronization for multi-device accessibility. The tutorial guides users on setting up the Sync Gateway, configuring data routing and access control, and enabling data replication and real-time notifications using Xamarin as an example. The text concludes by noting that while the tutorial uses the Sync Gateway in "walrus mode" without cloud data persistence, future tutorials will address this limitation by integrating the Couchbase server for persistent cloud storage.