The Nutrition Information Label is there to give you an insight into the breakdown of the food in terms of energy content, protein, carbohydrates, sugars, fats, sodium and other times may include fiber and other vitamin or mineral content such as iodine or iron. If the product is making any health claims such as 'high calcium', it needs to list calcium on the panel aswell. 

Generally the 3 main concerns to look for is the 3 S's 

-Sugar

-Saturated fat

-Salt/ Sodium

and try find the product with the lowest amount. 

 

Why? Because these have the greatest health risks. For example added sugars cause an increase in diabetes, tooth decay, fatty liver and high triglycerides. 
-Aim for less than 10g sugar per 100g. 

Be careful of cereals, biscuits, drinks (per 100mls), yoghurts, snack bars. 

 

Excess sodium causes increased pressure on kidneys and thus raises blood pressure, especially if adequate fluids like water are not high or enough fruit and vegetables containing the balance electrolyte potassium are not met. Your kidneys help regulate blood pressure which reduces risk of cardiovascular disease and stroke. 
-Aim for less 450mg of sodium per 100g. 

Be careful of sauces, processed meat, soups, stocks, bread, wraps, chips, crackers, cheese, noodles. 

 

Saturated fat from animal sources can reduce risk of cardiovascular disease. Saturated fat in small doses such as found in natural yoghurt, milk, cheese but avoid excess red meat with alot of saturated fat. For example choose leaner cuts of meat or mince or non streaky bacon. Processed meat products like ham, salami, luncheon are also high in sodium so best to keep to a minimum. 

-Aim for less than 10g per 100g for saturated fat. 

Be careful of bacon, red meat, processed meat, cheese

Getting your dose of healthy fats from plant sources is best such as avocado, nuts, seeds, olives or olive oil, coconut. 

Sometimes it can be tricky if the product is high in one thing but low in another. For example you may find a cereal that is high fiber, low fat, low sodium but really high in sugar, best to go for the low sugar option. 
Same with crackers, sometimes they can be low in fat, high in fiber but high in sodium. Then one must decide you may not eat 100g of the crackers and will be fine to have a few. Important to keep to portion size.

 

In general- 

-Cereals or snack bars you want to watch for the sugar content, 

-Sauces, noodles, meats, wraps look at sodium

-Cheese or meat or pastry products look at saturated fat content. 

 

 Also the important note on the ingredients list is do look at this! If you can't understand it with numbers and additives, it is a good reason not to eat it. The ingredients list tells you the bulk of the product from the most (listed first) to the least (listed last). So if you see sugar listed first or second in the ingredients list, you know to put it back down. 

Lastly it can be a good idea for portion size to be aware of the energy content per serve. If you are trying to lose weight or are not active, it can be ideal choosing the lower energy product to keep within your daily calorie intake. For example choosing a smaller wrap than a larger one or looking at the tuna flavours and seeing which has the least amount of energy.