Flask-RESTful is a Flask extension that simplifies the process of building RESTful APIs by abstracting away HTTP boilerplate code and providing a clean interface for parsing arguments, formatting output, and organizing routing. It aims to give developers a simple and extensible starting point for building their API while staying out of the way of business logic. The framework provides features such as flexibility and maintainability, performance and asynchronous processing, and better tools and libraries to help build modern APIs. By using Flask-RESTful, developers can keep their existing business logic and model code intact and decouple the processing of requests from the rendering of output.