Take 100 kcal of any food. Add up the share of your daily need it covers for ten nutrients. That sum is the nutrient score. Higher and further right is better. Pick a category to see who lives where.
Each nutrient contributes the percentage of your daily requirement that 100 kcal of the food delivers, capped so one freak vitamin cannot carry a food on its own. The ten percentages are added up.
The score is per 100 kcal, and 100 kcal of palak is nearly half a kilo of it. Curry leaves outscore chicken breast, but nobody eats them by the bowl. A high score counts only in quantities you can actually eat, which is why the dot size shows a practical serving.
Up means more nutrition per calorie. Right means more protein per calorie. Staples sit bottom left because their job is calories. Fish, liver and leafy greens sit top right because they do everything else.
A dal, a sabzi, some curd and two eggs do the nutritional work the rice does not. If you eat meat, liver and small fish give you more per rupee than anything else on this chart.