In certain situation, TAD would want the shape of an object to be internally represented in a clockwise fashion. This is useful, for example, when you want to merge objects together into one union.

How to know what is the current direction of the shape?
Simple. Press F3 repeatedly, and notice how the first helper (the red square dot) is moving. If that is moving clockwise, then it means the shape is already drawn clockwise. Else, no.

When you use this command, the area and perimeter will not change of course. Only the way the shape is internally represented would get flipped around if so required.

There is an equivalent command in the sub-menu to convert a shape into anti-clockwise order

If you thought you were wrong about this, you can always undo this.

WARNING
If the shape contains non-linear edges (i.e. curves) then you may find that the curve may have shifted to another edge when you convert the shape to clockwise or anticlockwise order. That means, you may need to remake those edges which had curves

See also: Merge