A slide stroke is a “smooth, continuous movement” when moving the paddle.
The hands are held toward the center of the loom. As the stroke begins on the left, the left hand remains on the loom and the right hand is allowed to slide out to the edge of the paddle. The left hand pulls, the right hand pushes, the torso rotates to the left and the left foot pushes off the footpeg to transfer the energy to the hull. At the end of the stroke, the paddle is swung to the other side as the right hand returns to meet the left at the loom and the motion is mirrored on the right side. In actual practice the hands do not usually touch in the center and the blade is usually grasped a comfortable distance and not necessarily at the edge of the blade.
Slide stroke is often used to accelerate the kayak, to assert more power to the paddles. Storm-paddles are usually applied with this technique to reduce wind resistance.