On the mountain of Sinai, G‑d communicates to Moses the laws of the Sabbatical year: every seventh year, all work on the land should cease, and its produce becomes free for the taking for all, man and beast.
Seven Sabbatical cycles are followed by a fiftieth year—the Jubilee year, on which work on the land ceases, all indentured servants are set free, and all ancestral estates in the Holy Land that have been sold revert to their original owners.
In this week's Parshah, Behar, we learn about some very important mitzvot that apply in the land of Israel.
First is shemittah. The same way the seventh day of the week is Shabbat, every seventh year is a Shabbat for the land when the land gets to "rest." This means that for six years, farmers may work on the land, sowing seeds so things should grow, pruning to help the plants grow better, and harvesting the fruit and vegetables so they can sell it and make money. But in the seventh year, the year of shemittah, the land must be allowed to rest, and there can be no planting or harvesting. Instead, anything that grows becomes free for anybody who wants to just pick and enjoy.
After seven cycles of shemittah, the fiftieth year (7 x 7 = 49, it's the year following the 49th, so it's the 50th), is called yovel or the jubilee. It is also a year of rest for the land, but in addition to that, all servants go free, and all property returns to its original owner. That means that whenever somebody buys a plot of land he knows he will only keep it until the year of yovel when the land will go back to the original owner.
Then the Torah tells us that we shouldn't worry that we won't have enough to eat during shemittah and the following year because we can't plant and harvest. Because G‑d promises that the year before shemittah--the sixth year--will produce enough food for three whole years--the sixth year, the year of shemittah, and the following year, when things won't grow because there was no planting during shemittah.
We also learn in this Parshah that it's forbidden to charge a Jew interest. That means that when we lend someone money, we can't take a little extra back as a thank you for doing them the favor and lending them the money. Rather, all loans must be free--the person only has to pay back exactly what you lent them.