Leviticus 25

"And you shall count seven sabbaths of years for yourself, seven times seven years; and the time of the seven sabbaths of years shall be to you forty-nine years...And you shall consecrate the fiftieth year, and proclaim liberty throughout all the land to all its inhabitants. It shall be a Jubilee for you; and each of you shall return to his possession, and each of you shall return to his family.  That fiftieth year shall be a Jubilee to you; in it you shall neither sow nor reap what grows of its own accord, nor gather the grapes of your untended vine.  For it is the Jubilee; it shall be holy to you; you shall eat its produce from the field."  vv.7-12

Read chapter 25. 

"The word jubilee signifies a peculiarly animated sound of the silver trumpets. This sound was to be made on the evening of the great day of atonement; for the proclamation of gospel liberty and salvation results from the sacrifice of the Redeemer" (Matthew Henry's Concise Commentary). What a cool way to give land rest and rejuvenation while it also still provides.  Every seven years the land would have rest for one year so that meant in the sixth year one would harvest enough for two years.  Then seven times of these seven years (7 x 7 = 49) would be the year of Jubilee and would be another year of rest for the land, so that last set of seven would be followed by two years of rest, the seventh year plus the Jubilee year.  The year of Jubilee was more than just rest for the land but a year of freedom.  No longer was the slave enslaved, no longer was debt held against someone.  People returned to their families and regained possessions that were once theirs.  This was probably done for preserving families, genealogies, and tribes, and preserve the land originally given in dispersion of the Israelites.  I don't think the Israelites ever made it to the year of Jubilee because of sin and turning from the Law:(  What do you imagine the year of Jubilee like in the hearts and minds of people?