'Wáng yáng bǔ láo' is a classical Chinese idiom literally meaning 'lose sheep, then repair the pen.' It originates from an ancient fable in which a shepherd neglects his fence, loses sheep to wolves, and only after the loss fixes the enclosure. Though the damage has already occurred, the act of mending prevents further loss — conveying the idea that it’s never too late to correct a mistake or address a problem, even after consequences have begun.

The four characters combine meaningfully: 亡 (wáng) means 'to lose' or 'perish'; 羊 (yáng) means 'sheep'; 补 (bǔ) means 'to mend' or 'to repair'; and 牢 (láo) means 'pen,' 'enclosure,' or 'stable.' As a noun phrase, it functions as a set idiom — not used verbally or adjectivally — and appears most often in reflective, advisory, or didactic contexts, such as giving advice, analyzing policy failures, or encouraging timely remediation.