PubNub Functions offers a serverless environment for managing real-time message routing, filtering, and transformation over the PubNub Data Stream Network, allowing users to control message processes without additional server complexity. This tutorial demonstrates using Functions to implement debouncing in a Smart Doorbell app built with React Native, preventing repeated mobile push notifications by removing push notification keys from messages sent within 30 seconds of each other. Functions execute JavaScript event handlers on in-transit messages or via RESTful APIs, facilitating secure API calls, reducing latency, and enabling global message translation and audience interaction. By utilizing PubNub's edge-based processing capabilities, developers can focus on product development without managing infrastructure, reducing time to market and costs. Users are guided to create a PubNub-powered IoT smart button and React Native app, and to set up a "Push-Filter" function that ensures messages are only sent once every 30 seconds, demonstrating the effectiveness of Functions in enhancing app functionality while maintaining simplicity.