Ray was a Force technique used by Jedi skilled in energy manipulation. By managing this power, a Jedi could turn small amounts of nearby matter into energy that could be controlled. With this energy, a Jedi could block attacks from blaster bolts.
Ray could also be employed to stop lightsaber attacks, although stopping a fast-moving lightsaber at close range could be highly dangerous and would most likely fail. Using another lightsaber instead was generally a more desirable option. Only experienced Jedi could use ray effectively.
Energy collected from this ability would dissipate if used to absorb too much energy, disappearing in the form of a flash of heat.