soft and hard generaly refer to the depth of the defender relatiave to the receiver. A defender may be playing man coverage but begin is alignment 5 yards deep. This would be an example of soft man. THe defender is going to give up short throw to rally and tackle to avoid being beat deep.
Many coaches will play split field coveages, so that you have one side playing man and another side playing a zone. A common adjustment to cover 2 vs a 3x1 set is to push the zone over a man. Now the single side will play a man coverage and the trips side can still play cover 2 without the fear of the vertical route . The single side may play as soft man, because he has no safety help, or he may play a press man (hard)
this is a real general answer.