The left side menu ... I did not understand what's good for. The first impression was that selecting a site component will show that component live on the right

The left side menu ... I did not understand what's good for. The first impression was that selecting a site component will show that component live on the right side with WYSIWYG-like editing. Than realized this is not working, or was not designed to work such way. It was just a quick overview maybe if I would have more time I could figure out better.