E-brake, handbrake, or parking brake is just a cable connected to the rear brakes of the car, when you pull the handle, the rear brakes are engaged. Applying the e-brake will change the car's momentum, shift the weight to the front of the car. Depends of the speed of the car, the wieght shift could cause the rear wheels to loose (some} traction, hence could make the "tail swing out". Some people use it to induce oversteer, some uses it to slow down the car before a turn. That is how it works in a nutshell, I think.