There are two interpretations of this phrase, though some sources give only the first interpretation.
In the first interpretation, it refers to the fact that both cast-iron pots' and kettles' bottoms turn equally black when hung over a fire, and thus the pot is accusing the kettle of a fault it shares.
In the second, subtler interpretation, the pot is sooty (being placed on a fire), while the kettle is clean and shiny (being placed on coals only), and hence when the pot accuses the kettle of being black, it is the pot’s own sooty reflection that it sees: the pot accuses the kettle of a fault that only the pot has.
Japanese: 目糞鼻糞を笑う(ja) (めくそはなくそをわらう, mekuso hanakuso o warau) (the sleep in one's eyes laughs at the snot in one's nose), 団栗の背比べ(ja), どんぐりの背比べ(ja) (どんぐりのせいくらべ, donguri no sei kurabe) (height comparison among acorns), 猿の尻笑い (さるのしりわらい, saru no shiri warai)
The translations below need to be checked and inserted above into the appropriate translation tables, removing any numbers. Numbers do not necessarily match those in definitions. See instructions at Help:How to check translations.
Mandarin: (please verify)烏鴉笑豬黑，自己不覺得(the crow mocks the blackness of the pig, ignoring its own blackness)(Sichuan), (please verify)龜笑鱉無尾(The turtle makes fun of the trionychidaes that they are of short tails)(Zhangzhou, Fujian)