What does Om mean?
From Sanskrit Om (ॐ), the sacred primordial sound and mantra regarded in Hindu tradition as the essence of the universe. Used as a name it carries that whole spiritual weight.
What does Ishan mean?
From the Sanskrit ईशान (īśāna), 'ruler, master'. It is an epithet of the god Shiva, also denotes the sun and the north-eastern quarter (one of the dikpalas). A genuine, well-attested Vedic/classical term.