From the perspective of Jewish law, ownership of a field is made up of two separate elements: ownership of the field itself (referred to by the Gemara as kinyan ha-guf) and ownership of the use of the field and its produce (referred to by the Gemara as kinyan peirot). Generally speaking, these two elements of ownership go hand-in-hand, so that the owner of the field controls both. On occasion, however, a person may purchase only one of those elements, leaving the other one in the hands of the original owner.
One classic example of this is the case of selling a field at the time when the yovel – the Jubilee year – was in force. At that time, an ancestral field that was sold automatically returned to the seller (or his heirs) when the yovel arrived. Thus, someone who sold a field retained the kinyan ha-guf – he still owned the land itself – and what he sold was merely the kinyan peirot – the right to the fruit produced by the land. With the arrival of the Jubilee year, the land is returned to its original owner and the two elements of ownership are, once again, in his hands.
The question raised by the Gemara on today’s daf (=page) is whether or not kinyan peirot ke- kinyan ha-guf dami – whether the individual who owns the element of the produce and use of the field is considered to also have some level of rights regarding the field itself. According to this approach, the true owner who has a kinyan ha-guf in the field is, nevertheless, limited with regard to what he can do with it. If the kinyan peirot is not considered to be kinyan ha-guf, then the true owner can choose to sell his land, even though the purchaser would not get full ownership until a later date.