This tutorial teaches developers how to add a kill switch feature to their Sinatra applications using the LaunchDarkly Ruby SDK. The process involves creating a new Ruby project, setting up a simple Sinatra application, and integrating the LaunchDarkly Ruby SDK to manage external API calls. The tutorial also covers configuring Puma to ensure that LaunchDarkly flag changes take effect immediately. By following these steps, developers can create a flexible and responsive application that can quickly disable external dependencies during emergencies or unexpected issues.