Roasted peanuts ground into a thick paste, smooth or crunchy, usually with salt, sugar and oil mixed in. Spread on bread, and stirred into sauces as a seasoning.
花生 (peanut) literally means 'flower-born' because peanuts grow from flowers that bend down into the soil. Adding 酱 (sauce/paste) gives you the spread. Other 酱 foods: 芝麻酱 (sesame paste), 辣椒酱 (chili sauce), 番茄酱 (ketchup).