The tension map is a color coded map on the garment showing the tension in each part of the garment, based on the physics of the fabric:
White means no tension, and red means the most tension.
A pop-up menu defining the color values in gr/cm^2 is displayed when enabling the Tension Map.
Closing the pop-up menu exits the Tension Map viewing mode.
Hovering the cursor over the garment displays a pop-up screen with Max Stretch in length and width directions:
You can use the tension map to help you identify parts of the design that may need to be changed to achieve a better fit.