This mantra has no approximate translation. The sounds related directly to the principles which govern each of the first six chakras on the spine...Earth, water, fire, air, ether.
Notice that this does not refer to the chakras themselves which have a different set of seed sounds, but rather the principles which govern those chakras in their place. A very rough, non-literal translation could be something like, 'Om and salutations to that which I am capable of becoming.'
This mantra will start one out on the path of subtle development of spiritual attainments. It is the beginning on the path of Siddha Yoga, or the Yoga of Perfection of the Divine Vehicle.