if you are not too thin and not too fat, then you have a normal weight. an amount of 'normal weight' kilos depends on you height and age. if you are grown up (18 y.o.+) and you need to know your perfect (desirable) weight you need to subtract 110 from your height in cm., the answer means your normal weight.
you can also use the body mass index calculator to calculate your body mass index (or BMI - google it) to recheck my results.
Person 1: My height is 5''7 and my weight is 133 pounds. Should lose some weight? I look pudgy!
Person 2: No! You have a normal weight!
Girl: My height is 164cm. and my weight is 65 kilos. Feel its rising! Is it ok?
Girl's BFF: It's ok, but you really should lose at least 10 kilos to reach your normal weight. Or you are going to look like shit in a couple years! Look at Jessica Simpson! Do you wanna look like that???
Girl: Oh gosh, of course I don't! I'll do my fucking best to avoid it!