莎丽 is a phonetic loan from Hindi साड़ी (sārī) via English 'sari' — a single 5-9 metre length of fabric draped around the body. The transliteration uses
莎 (a kind of grass; common phonetic 'sa-') and
丽 (beautiful), so the Chinese characters happen to read 'beautiful'. Mainland sources also write
纱丽 (with
纱 'gauze') to evoke the lightweight cloth — same pronunciation, different visual flavor.