The Rotate 0 degree reference rotates the 0 degree reference orientation by 90 degrees for all faces of a shell. The option is similar to the Rotate Orientation option but applies to all faces of shells simultaneously.
For the 3 point bend model, suppose you desire the 0 degree ply angle in the direction as shown by the black arrow.
However, the model below by default shows 0 degree ply angle as illustrated. See ply angle for understanding the different arrows of triads.
In this case, you select the Rotate 0 degree reference and get the desired result.
The option applies changes to all faces of a shell. To control each face separately see Rotate Orientation.