The MEAN Stack is a free, open-source JavaScript framework for building dynamic web applications, encompassing MongoDB, Express, Angular, and Node.js. MongoDB serves as the database system, Express is the back-end framework, Angular handles the front-end, and Node.js operates as the back-end runtime environment. This course covers key concepts such as Express.js fundamentals, Node.js, REST, CRUD operations, and integrating Express.js with MongoDB. It also delves into TypeScript, dependency injection, single-page applications (SPA), directives, pipes, promises, observables, and Angular testing.