'Block Spam Calls and Robocalls with Node.js' is a tutorial that guides developers on how to use Twilio's Add-ons Marketplace to block spam calls and robocalls using Node.js. The tutorial covers the basics of setting up an Express application, integrating third-party technologies through Add-ons, checking phone number scores in Node.js, making block call decisions, and configuring a phone number webhook. It also provides examples and tips for testing and debugging the application. The goal is to help developers build a robust system that can effectively filter out spam calls and improve customer service.