The Hermes engine, developed by Meta (formerly Facebook), is the default JavaScript engine for React Native apps intended to enhance performance and efficiency, especially for mobile applications. With the release of React Native 0.70, several key updates have been introduced, including a unified codegen configuration and support for new architecture libraries. The blog also discusses future trends in mobile app development, emphasizing the importance of cross-platform compatibility and the increasing significance of technologies like AI, cloud computing, and 5G networks.