ॐ पूर्णमदः पूर्णमिदँ पूर्णात् पूर्णमुदच्यते ।
पूर्णस्य पूर्णमादाय पूर्णमेवावशिष्यते ।
ॐ शान्तिः शान्तिः शान्तिः ॥

Meaning:
Om. That (supreme Brahman) is infinite, complete, and this (conditioned Brahman) is infinite. The infinite proceeds from the infinite, supreme Brahman. Through knowledge, taking the infinite from the infinite, conditioned Brahman, it remains as the infinite unconditioned Brahman alone. Om Peace, Peace, Peace! %alternate meaning (Alternate) OM! That is Full. This is Full. From that Full, this Full has come; when this Full is taken from that Full It always remains Full! Om Peace, Peace, Peace!

Word meanings:
ॐ = same as `OM’ i.e. the praNava or `o.nkAra’ mantra;
पूर्णमदः = complete, that;
पूर्णमिदँ = complete, this;
पूर्णात् = from the whole or infinite;
पूर्णमुदच्यते = complete, is produced;
पूर्णस्य = of the whole;
पूर्णमादाय = having taken the whole; the entire thing;
पूर्णमेवावशिष्यते = the whole thing itself remains;
ॐ = same as `OM’ i.e. the praNava or `o.nkAra’ mantra;
शान्तिः = Peace; tranquility;
शान्तिः = Peace; tranquility;
शान्तिः = Peace; tranquility;