Nutrition labels are required by law on packaged foods. Knowing how to read them is a foundational health skill.

Key sections of a nutrition label:

• Serving size — everything on the label is per serving. Check how many servings are in the package.
• Calories — total energy per serving
• Macronutrients — total fat, carbohydrates (including fiber and sugars), protein
• % Daily Value (%DV) — based on a 2,000-calorie diet. 5% = low, 20% = high.
• Ingredients list — listed in descending order by weight. First 3 ingredients dominate the product.

Red flags to spot:

• Sugar listed under multiple names in the first 5 ingredients
• Hydrogenated or partially hydrogenated oils (trans fat)
• More than 5 ingredients you can't pronounce
• Serving size manipulated to make numbers look better

Reference:

Wikipedia: Nutrition facts label

https://en.wikipedia.org/wiki/Nutrition_facts_label