your car radiator is leak!
but before that check by sliding down the car, where the leakage is coming from!
if leakage is from radiator then its better to replace it or service it.
in most simple cases the cork for draining of coolant becomes weak you ve to get a new cork!
drain the coolant yourslf and fix the new cork at bottom of radiator, cost is just 50 - 60 Rs Kabli!