Free swimming is when the fry no longer have a yolk sac and need to be fed. At that point, they should be swimming around. There are some species where the fry swim around with the yolk sac still unabsorbed ( arrawanas come to mind) but you dont need to feed them so they would not be considered "Free Swimming". All livebearer fry come out free swimming. Most cichlids ( especially S.A. ones) who are not mouth brooders will have fry that need to absorb yolk sac before they can swim at all.
Hope this helps