Pocket Base is a modern backend solution for UI development, providing functionalities such as creating collections, schemas, storing data in a database, authentication, real-time storage, and ease of use. It competes with headless UI backends like Superbase and Contentful, offering features like database management, ORM for queries, server setup, API development, file storage, and access control. This comprehensive solution eliminates the need for separate tools or services for different backend components, making it a convenient option for building applications and mobile apps.