The seed syllables oṃ āḥ hūṃ (pronounced “hung”) represent vajra, or wisdom, body, speech, and mind.
These syllables oṃ āḥ hūṃ adorn the forehead, throat, and heart of all Vajrayana deities, such as Chenrezig and Mañjuśrī. The syllable oṃ (ཨོཾ་) represents the union of form and emptiness. And āḥ (ཨཱཿ) represents the indivisibility of speech and emptiness. And finally, hūṃ (ཧཱུྃ) represents the union of pure awareness and emptiness.
And in Vajrayana, although deities may manifest in myriad forms, the essence of body, speech, and mind is precisely the same.