Kapalbhati pranayama is the breathing exercise where more emphasis is given on Exhalation through nose. For performing this Pranayama we have to exhale forcefully through our nose and let the inhalation happen through the nose happen naturally without our effort. The number of Exhale should outnumber the inhale.
Though there are so many health benefits, It could be contradictory for people with some health condition, so it is advisable to consult a teacher before performing.