This tutorial teaches how to validate Twilio Event Streams Webhooks in Java. It covers the process of creating a Java project using Spring Initializr, adding required dependencies, writing Java code for webhook validation, making the application publicly accessible on the internet with ngrok, setting environment variables, creating a Sink resource, testing the application, and subscribing to incoming messages. The tutorial emphasizes the importance of validating all input external to an application, including Twilio Event Streams Webhooks.