Hi, Carol. The black spots are probably a result of water that has gotten under the finish on your floor, so you will not be able to remove the stains without removing the finish. Some possible causes are pets and overwatering a plant. But basically it makes no difference where the water came from since the stain removal process is the same. If you will look down the board, you will find this topic covered many times over. Regrettably, sometimes the stain is so deep that it is not possible to remove it and boards have to be replaced. Unless you are relatively experienced in do-it-yourself projects, this is probably a job for a pro.