The ring was magically created by Zeus to allow Hercules the use his godly powers while on Earth. Without the ring, Hercules was a mere mortal that could be injured or mortally wounded.

When in serious danger, would Hercules put it on and raises his fist to the heavens. The ring was then struck by lightning, endowing Him with superhuman strength, durability, speed, reflexes, stamina, and endurance.

When not in use, Hercules kept his magic ring in his belt.