Elemental Shields is an ability used by the Ninja, and presumably can be used by all of the other Elemental Masters. As the name suggests, it surrounds the user in a protective bubble made of elemental energy, strong enough to survive any number of intense situations. This even includes being able to survive orbital impacts by absorbing the force of entering an atmosphere at nearly 6 million feet per second.
When Zane overheats while powering the rocket ship flying back to Earth, Lloyd shows the other Ninja the Elemental Shield technique to allow them to survive entering Ninjago's atmosphere. The other Ninja quickly follow Lloyd's example, using the shields to escape the exploding rocket and land in New Ninjago City.