This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 賲 is uncertain. It visually combines 保 and 貝, but the original semantic and phonetic roles are unclear.
The top 保 suggests protecting or keeping, and the bottom 貝 is a shell (money). Imagine guarding a treasure, but remember the actual meaning is uncertain.
For ホウ, picture a protective 保 (ホ) shell 貝 that you hold (ホウ) carefully: 保 -> ホ, and the whole shell is your treasure. The reading ホウ is like a long 'ho' sound.