You can tune the bass E string to octave E
The A string is tuned to octave A
The D string is tuned to octave D
The G also to octave G,which makes this middle string the highest tuned string on the guitar
The B is tuned normal,as is the treble E
There may of course be variations of this tuning.It works well as a second guitar,alongside a regular tuned guitar.If you're picking,it gets a little tricky,and lead runs...well,you have to remember that you're in different territory.Some early Emmylou Harris albums have featured this tuning for example.Somebody here may contradict all this,but thats ok.We're always learning.Good luck.
David