This switch is set to true to limit the tool between two angles starting from toolpath slice normal vector. In other words, imagine 2 cones with different opening angles w1 and w2. The tool axis direction is enforced to be between these 2 cones. The orientation of the cones depends on the cone axis settings. You can set the orientation to x, y and z direction as well as to a user defined direction.
If your toolpath is related to leading curve like "cuts along curve" you can set the cone axis to "dynamically using leading curve". Then you can limit the tool axis along this curve and its toolpath.
This is a typical example
for tube milling. You see the leading curve running through the tube.
Toolpath pattern is set to "cuts along curve" which gives you
parallel cuts through the curve. With the dynamical limits setting you
can now force the tool between the angles and avoid collisions for example.
Without having gouge check activated.