noun
A variety of kidney bean with a reddish-purple skin, commonly used in Japanese cooking for sweet dishes like ぜんざい or 甘煮.
金時豆を甘く煮て、おやつに食べる。
I simmer red kidney beans with sugar and eat them as a snack.
インゲン豆 is a broader term for common beans (Phaseolus vulgaris), while 金時豆 specifically refers to the red kidney bean variety.
The name 金時 (Kintoki) is said to come from the legendary strongman Sakata no Kintoki (金太郎), known for his red skin, which resembles the bean's color. 豆 means 'bean'.