For example if u have to lose belly fat, do someone need to do belly fat exercise every day?

No you don’t. No exercise can target a specific area of your body to lose fat, those exercises might help just because they get you moving. We actually ‘lose’ fat through our breath (pretty crazy but awesome), so any exercise that gets you breathing heavy and your heart rate up will help to lose fat. Don’t obsess over losing fat though, make your goal to be healthy, which includes not overeating and reducing food high in fat and salt (so ready meals and takeaway if possible). The best way to lose weight if you need to is to be in a calorie deficit I.e. burn more than you take in. If you are concerned about your health I suggest talking to your doctor for advice.