what @velocityc6said. In the most basic sense .. it is throttle control and brake control.
"The system lightly brakes the outer wheels to help restore the vehicle to going in a straight line (keep in mind that when you are coming out of a turn, your outer wheels are moving faster than your inner ones). "
the video on this page (G-VECTORING CONTROL – MAZDA NORTH AMERICAN OPERATIONS – DAVE COLEMAN PRESENTATION) should give you a bit more insight. It gets really interesting around the 9 minute mark and forward.
what the industry says.. some of the same info as above:
G Vectoring Plus may be different, but the original 2nd gen G Vectoring Control was modulating throttle, not brakes, to provide the inertial adjustment. I didn't follow the links today, this is based on watching Dave video from a couple years back.
Sounds like an effort to promote understeer. I would be interested in seeing how it reacts on an awd cx5/3 with stiffer suspension and larger sway bars easily capable of mild oversteer