hi,
is it advisable for one to exercise everyday? will we collapse ? i m doing bodycombat, can i do it everyday?

yes, its ok to exercise (CV-wise) everyday, but only you can tell if your body can take it. depends on how well you eat, current level of fitness, how quickly your body tends to recover etc. if it feels like its too much, it probably is. if you feel ok, then there's no reason not to do it. i'd probably avoid doing bodycombat everyday though since it's quite high intensity. give yourself at least a day ot two of lower intensity exercise.

what would happen if we overdid it

You explode. . .

Well its not good to overtrain, its bad for your body. Just eat well & exercise 30min to an hour a day and you'll be good.