Brief Explanation
1: Om, That Purna (That Supreme Consciousness is Full); This (Universe) is also Purna (Full with the Supreme Consciousness); From Purna is manifested Purna

From the Fullness of Supreme Consciousness the Full Universe is manifested. Just as a drop of water in the rain has the same qualities as the water in the Ocean. Every particle in the Universe has the same qualities as that Supreme Consciousness.

2: Taking Purna (Full Universe) from Purna (Fullness of the Supreme Consciousness), Purna (Supreme Consciousness remains ever Full) indeed remains.

Just as the Ocean remains ever Full even though water is taken from it in the form of clouds, the Supreme Consciousness remains ever Full even though the Universe manifests from that Supreme Consciousness),

3: Om, Peace, Peace, Peace.