The sabbath year is the seventh year of the seven-year agricultural cycle mandated by the Torah. During shmita, the land is left to lie fallow and all agricultural activity, including plowing, planting, pruning and harvesting, is forbidden by Jewish law. Any fruits or herbs which grow of their own accord and where no watch is kept over them are deemed ownerless and may be picked by anyone. All debts, except those of foreigners, are to be remitted.
Leviticus 25:1-7 promises bountiful harvests to those who observe the shmita.
The next Shmita year is 2021-2022 (5782). (Wikipedia)
Six years you shall sow your land and gather in its yield; but in the seventh you shall let it rest and lie fallow. Let the needy among your people eat of it, and what they leave let the wild beasts eat. You shall do the same with your vineyards and your olive groves. (Exodus 23:10-11)
The LORD spoke to Moses on Mount Sinai: Speak to the Israelite people and say to them: When you enter the land that I assign to you, the land shall observe a sabbath of the LORD. Six years you may sow your field and six years you may prune your vineyard and gather in the yield. But in the seventh year the land shall have a sabbath of complete rest, a sabbath of the LORD: you shall not sow your field or prune your vineyard. You shall not reap the aftergrowth of your harvest or gather the grapes of your untrimmed vines; it shall be a year of complete rest for the land. But you may eat whatever the land during its sabbath will produce—you, your male and female slaves, the hired and bound laborers who live with you, and your cattle and the beasts in your land may eat all its yield. You shall count off seven weeks of years—seven times seven years—so that the period of seven weeks of years gives you a total of forty-nine years. Then you shall sound the horn loud; in the seventh month, on the tenth day of the month—the Day of Atonement—you shall have the horn sounded throughout your land and you shall hallow the fiftieth year. You shall proclaim release throughout the land for all its inhabitants. It shall be a jubilee for you: each of you shall return to his holding and each of you shall return to his family. (Leviticus 25:1-7)