The speaker, Olivier, introduces Slint, a native user interface toolkit for desktop and embedded platforms that is implemented almost completely in Rust. Slint uses its own domain-specific language for UI design, which can be learned as easily as any API, and has bindings to various programming languages including C++ and JavaScript. Slint also includes auto-completion, go to Symbol functionality, and a live preview in the code editor, making it a visually interactive UI toolkit. Furthermore, the speaker demonstrates that Slint is lightweight by showcasing its ability to work on a microcontroller with <3KB of RAM. The project is open source and has multiple licensing options, including both GPL and commercial licenses, and is expected to release version 1.0 this month with intentions to improve the preview and create a design tool for non-technical designers.