This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
姲 combines 女 (woman) with 安 (peace/calm), likely a phono-semantic compound where 安 contributes the sound and the idea of tranquility related to a woman. The exact historical development is uncertain.
A woman 女 beside peace 安 suggests a calm, peaceful woman, but the kanji's meaning is unclear.
For アン, imagine a peaceful woman named Ann: Ann -> アン, and she embodies the calm of 安.