It's a boilerplate for a project that uses react (https://facebook.github.io/react/), redux (https://rackt.github.io/redux/) and redux-undo (https://github.com/omnidan/redux-undo).

I've configured it so that it uses hot reloading (only refresh the parts of the web app that changed) plugins that also show the error in the browser while you're developing.

Does that clear it up a bit? :)