 So you don't understand polyloops and polygroup, not a problem. This is the exact same thing as polyloop with a polygroup constraint. So it's going to apply your action to a polyloop, but only to faces that are the same color as the one you clicked. So you can see here we have a cube, it's got two red faces and two green faces. So if we left click on red, it's going to extrude a loop, but the loop stops when there's no more red faces. Same thing if we go to the green side, if we left click it's going to extrude a loop, but only as long as there are green faces. So, hope that helps and as always I hope you have a fantastic day and I'll see you around.