Redis is an open-source, in-memory data structure store, used as a database, cache, and message broker. Coursera's Redis skill catalogue teaches you the fundamentals of working with Redis, and its application in real-world scenarios. You'll learn about various data structures, Redis' architecture, building high-performance applications using Redis, and managing in-memory datasets. You'll also gain insights into using Redis with various programming languages, designing data models, and implementing a distributed caching system. This knowledge will be invaluable in improving the speed, reliability, and performance of your web applications and services.