This tutorial guides developers through the process of building a COVID-19 data tracker WhatsApp chatbot using the Twilio API for WhatsApp, PHP, and Symfony. The chatbot uses an open-source API to retrieve COVID-19 cases statistics from different countries and sends a summary of these cases back to the user via WhatsApp. To build the chatbot, developers need to set up a new Symfony application, install required dependencies, configure Twilio's WhatsApp sandbox, and create a controller that handles incoming messages and sends responses back to the user. The tutorial also covers how to integrate ngrok for exposing the local server to the internet and setting up the webhook for the chatbot.