Rare, formal, and somewhat dated term for a prostitute. Modern Japanese typically uses 売春婦 or 娼婦 instead.
The word 売笑婦 can be found in old documents.
Compound of 売 (bai, 'sell'), 笑 (shō, 'smile'), and 婦 (fu, 'woman'), literally 'a woman who sells smiles'. The exact historical derivation is uncertain; the spelling is conventionally associated with the meaning.