syllable
This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
唵 combines 口 (mouth) with 奄, which likely contributes the sound. The exact historical development is uncertain.
A mouth 口 beside 奄, a shape that appears in many rare characters. The meaning is unclear, so treat it as a syllable marker.
For アン, imagine an ant (アン) crawling out of the mouth 口: ant -> アン, and the ant makes a tiny syllable sound.
om (ritual chant in Hinduism, etc.); aum