Next follows the Kshatra. Verily, breath is the Kshatra, for breath is Kshatra, i.e. breath protects (trayate) him from being hurt (kshanitoh). He who knows this, obtains Kshatra (power), which requires no protection; he obtains union and oneness with Kshatra.

In plain words: Breath is Kshatra, meaning power and protection, because breath protects a person from harm. Whoever knows this gains a power that needs no protection and becomes one with it.