This exercise introduces kumbhaka into your breathing practice. Kumbhaka is retention or suspension of the breath. It is the phase between inhalation and exhalation. Kumbhaka is the confining of the prana inside.
The practice of kumbhaka is less about breath control and more about mind control, about learning to stop the breath as a means of learning to stop the incessant activity of the mind.

This exercise is a combination of viloma, interrupting the inhalation and kumbhaka, retention of the inhalation.vvRemain undisturbed, mentally equanimous, during kumbhaka. Adopt an agreeable demeanor as you apply intense focus to the suspended gap between breaths.