Dragon Ball Z/Super follows the adventures of the adult Goku who along with his companions, defends the earth against an assortment of villains ranging from intergalactic space fighters and conquerors, unnaturally powerful androids and near indestructible magical creatures.
Ki is also known as “latent energy” or “fighting power,” which directly translates as “life force.” This force is a tangible energy inside every living being, with its major focus being in the center of the body. By drawing it out, an individual is able to manipulate it and use it outside the body. Ki can be used for many different techniques. Because there are physical limits to the strength of the body itself, it is necessary to increase one’s ki to overcome this barrier and become stronger. Usually, the more concentrated the masses are, the more time the user requires to draw it out by powering up. When fighters gather ki, they are able to gain enhanced strength, speed, endurance, and can increase the power of their attacks to inflict greater damage to opponents. Normally, the more the ki is increased, the harder it is to control, so ki control is also important. Energy can be lost when the user sustains injuries, as exclaimed by Gohan when he loses over half of his maximum energy supply when hit by Cell’s Time to die. Maintaining proper balance between the body and spirit is important in utilizing energy, and the more properly balanced they are, the more energy you can project.
Ki sensing is the ability to sense the location, life force, and power level of anyone; the stronger and closer the enemy, the more powerful the sensation. Also, if a ki is very powerful, it can be sensed from afar by people who are trained to sense energy
The concept of ki/chi exists in martial arts – typically eastern ones and practices related to healing.
It does not allow you to shoot balls of energy. There are people who claim to heal with chi, and there are people who claim that they use it in fight – for achieving resistance to wounds or making limb/body “unbendable”.
It is unclear whether this is something that actually exists or a mental construct that instructs your body to work in a specific way (some of the stuff is similar to “autogenic training”, for example). The other thing is, that some of the supposed effects are very easy to fake when filming. So unless you run into a ki user yourself, you won’t know if it is real or not. If you do run into such user and experience the effects, then nobody will ever believe you, obviously.