Ultra Instinct is an ultimate technique that separates the consciousness from the body, allowing it to move and fight independently of a martial artist's thoughts and emotions. It is an extraordinarily difficult technique to master, even for the Hakaishin. However, angels like Whis appear to have mastered it. As a result, it is known as the "state of the gods"
This technique uniquely manifests as a transformation in Son Gokū and is his most powerful form, transcending Super Saiyan Blue. Despite this, Beerus and the other gods recognize the transformation's completed form, hinting that it might not be completely unique to Gokū