calories and a deficit?

i have been trying to figure this all out and go through the posts and see if anyone has explained it but i really cant. I am a little lost. what is my deficit supposed to be i eat between 1500 to 1200 calories a day and i am 5'3 and a half. Please i just want to fully understand this

anyone? i am sorry i know this is probably just common sense but i just dont know..

The deficit is the difference between the amount of energy (calories) you need to maintain your weight and the amount of energy you take on board to lose weight.   One is less than the other. 

The amount you need to maintain your weight depends on your height, age, weight and activity level.  If we say that's 2000 (which is a good working average assuming you're not obese or doing heavy-duty exercise) and you're consuming 1500-1200 per day then your deficit is between 500 and 800.   That is the right level at which to lose weight safely and steadily.