The data layer plays a crucial role in microservices architecture, as each service manages its own private data store. Understanding this concept is essential for building scalable, manageably, and resilient applications. The authors of the new e-book "Redis Microservices for Dummies" discuss how Redis can be used to optimize the data layer and eliminate the need for a separate primary database. By using Redis, developers can simplify their architecture and reduce development time. The Redis Stars Podcast also provides insights into real-world use cases of Redis in microservices architectures.