凯乐 (kǎi lè) is a transliteration of the English word 'kale', a leafy green vegetable. It is a loanword that appears primarily in culinary or health contexts, often in menus, grocery stores, or nutrition discussions. Unlike some other loanwords, it has no extended cultural or slang meanings — it refers directly to the vegetable itself. Use it where you would use 'kale' in English.