How many calories you need each day to lose weight depends on your activity level (both exercise and the rest of the day). A lb of fat is equal to 3500 calories, so to lose 2 lbs per week, you’ll need to burn 7000 more calories than you take in (roughly 1000 calories per day). Do this through a combination of reducing your calories and exercise. Otherwise, you’ll end up eating so little, you’ll be miserable and unlikely to maintain that diet long enough to see success.
It really depends on many factors, like the exercise your doing (amount, intensity, frequency, etc) and also the type of calories your eating -- meaning quality of nutrients. A few simple tips to try - start each meal (and snack) with a vegetable and/or fruit and make sure each meal (and snack) has a source of lean protein as well. This is just a start. Good luck!