洗手 literally means 'to wash hand(s)' — the verb 洗 (xǐ) means 'to wash', and 手 (shǒu) means 'hand'. Though 手 is grammatically singular, 洗手 is always used in the unmarked plural sense ('hands') in standard Mandarin, reflecting the natural physical action of washing both hands. It’s a common daily hygiene practice deeply embedded in Chinese health culture, especially emphasized before meals, after using the restroom, or upon returning home.

The phrase functions as an intransitive verb in most contexts — it doesn’t take a direct object (you don’t say *洗手手* or *洗手它*). It frequently appears in imperative instructions ('Please wash your hands'), habitual statements ('She washes her hands before eating'), and public health messaging. Unlike English, which sometimes uses 'wash one’s hands' for metaphorical meanings (e.g., disengagement), 洗手 is almost exclusively literal and physical in everyday usage.