This is a secret taijutsu of the Hyūga clan's main house, traditionally only known by the head of the clan and the clan's heir. Neji Hyūga, a member of a branch house, was able to learn this technique through mere observation, a testament to his genius. The moment before the Hyūga is struck by an attack, they emit chakra from all of their body's tenketsu to block it. They then spin rapidly, repelling the attack (and anything else in the vicinity) away and creating a protective shield for as long as they continue to spin. The greater the force of an attack, the greater the force with which it's repelled.
Revolving Heaven is meant to compensate for the blindspot of the Hyūga's Byakugan. But in this regard it is quite effective, leading Tenten to describe it as an absolute defense superior to the Shield of Sand. With greater skill seemingly comes greater range for the chakra shield; Neji can only block attacks just outside arm's reach, whereas Hiashi Hyūga can repel attackers from several feet away. The only effective means of countering the Revolving Heaven is to prevent the Hyūga from spinning; the anime sometimes depicts it being used without spinning.
"Kaiten" (回天, Literally meaning: revolving heaven) is a term used to refer to turning the tides or fighting back up from a weak position. When written as "回転" (kaiten), it means "revolving" or "spinning".
In the anime, Revolving Heaven is stated to reach speeds of up to about 1200 km/h (745.6 mph). If an opponent can exceed this speed in the direction of the rotation, it will breach the defence.
In the anime, if the user does not have focus and precise chakra control when the Revolving Heaven is executed, the user will repel themselves out of the technique.