From Japanese 彩 (sa) meaning "colour" or 佐 (sa) "aid, help" combined with 桜 (o) meaning "cherry blossom" (usually feminine) or 夫 (o) meaning "man, husband" (usually masculine). Other kanji combinations are possible.
From Ancient Greek σαώ meaning “rescuer”, itself from σῶς “safe and sound, alive and well”. This was the name of a Nereid, one of the fifty nymphs born to Nereus and Doris in Greek mythology. A moon of Neptune was named after her.