In ice skating, friction is used to start a stroke. As you angle your foot outward and extend the knee, the inside edge of the blade encounters the ice and the friction between the ice and the blade enables you to encounter resistance as you scrape the blade across the ice. You exert a force from the edge into the ice. Friction enables the edge to grip into the ice. The equal and opposite force of the ice onto the edge acts to propel the skater forward with kinetic energy.
Friction is invaluable in stopping on ice skates.