This is the directory that you are going to be using for your virtual machince. Everything inside this directory will be shared with VM. You can add/delete and modify any file except for the file called Vagrantfile. Once you call vagrant up you will not be allowed to modify this file. This means that you can't move, delete or rename it. This also applies to this directory. So before starting uop your VM for teh first time make sure its on a place on your computer that you like.
Inside this directory you will notice that there is a directory called CS61. In there you will find all the templates for the labs and assignments. It is required for the course that you use them.