These are predominantly animal fats that are usually hard at room temperature. Foods high in saturated fats include biscuits, cakes, ice cream, cooking fats, vegetable oils and margarine, coconut oil and meats. Diets high in saturated fats can lead to high cholesterol. high cholesterol basically means that your body is saturated with fat, so it is storing some in your blood, which as you can imagine, is not good at high levels!
Sugars can be disguised as all sorts of names including glucose, dextrose, sucrose, malactose and aspartame (a man made sugar). Sugar is a high GI food, your body processes it rapidly, usually meaning a high energy kick, then slump. A diet high in sugar will lead to weight gain.
For those who exercise very regularly, salt is less of a concern, because you lose salt in your sweat. High salt diets can lead to high blood pressure and diabetes, so there needs to be a careful balance here.
Is exactly what it says. Fat is an energy store. High fat diets lead to weight gain. Be careful of fat content in foods, specially if the ingredients have a lot of man made additives and few natural ingredients. Fats protect the organs, provide insulation and coat nerves. Fats are also an energy source, but not as good as carbohydrate for energy.
A calorie is a unit of energy. Therefore, a food high in calories will give you more energy than on low in calories. What you need to decide, is whether you will, through exertion, need the calories of the level that is in that food. If not, it will be stored as fat.