VSC stands for vehicle stability control, which automatically adjusts the power at each wheel to prevent skidding or wheelspin so that the car will corner in the safest and most stable way. It is not present in Vitz (yaris) as far as my knowledge is concerned.
Super ECT is the auto transmission in Vitz (ECT: Electronic Control Transmission).This transmission, claimed to be highly efficient, has adaptive programming and improved driveability on hilly roads with a reduced number of gear changes. As for D2, in this mode the gear will not shift to 3rd, used if you want to climb or accelerate very quickly. L is low gear, in which it will not shift to 2nd and used for towing or extremely upslope or downslope driving