So, when combined, "Om Dum Durgayai Namaha" roughly translates to "I bow to the goddess Durga, the embodiment of power and strength".
This specific mantra is often associated with the aspect of the Goddess—the slayer of the buffalo demon Mahishasura. In this context, the recitation of "Om Dum Durgayei Namaha" is not merely a verbal exercise but a symbolic internal battle where the devotee calls upon Durga to slay the "inner demons" of ego, greed, anger, and laziness. om dum durgayei namaha