The repository is a combination of Underscore with the Foundation SASS and Javascript files. I have concatenated and minified the JS files and enqueued them correctly through the WordPress API. Similarly, I installed Compass, which watches the SASS folder and concatenates all styled files into a single CSS file.
Its a great starting point for people who like Foundation and want to write a WordPress theme the right way.
Underscore is a theme framework without any significant styling. It was made as a base for WordPress theme developers, by providing basic hooks and crucial theme functions.
Foundation is the most advanced frontend framework, which provides a nice mobile first grid system.