This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
嵭 combines 山 (mountain) with 旁 (side, nearby). The exact historical development is uncertain, but it likely relates to a mountain feature or a place name.
A mountain 山 beside 旁 something else: perhaps a crumbling hillside, but the meaning is unclear.
For ホウ, imagine a mountain path where you hear a hollow 'hou' sound echoing off the cliffs: hou -> ホウ.