RubyMotion is a toolchain that allows developers to use Ruby to build iOS applications. It works by compiling Ruby code to Objective-C and allowing it to run natively on iOS, providing access to the full iOS SDK. It aims to provide a simpler and more productive development workflow compared to Objective-C, while allowing apps to be fully compatible with the App Store. The document outlines RubyMotion's implementation, workflow, community resources and limitations.