Sanctions are restrictions on a group of persons or an entire state designed to "punish" the government of a country for violating international agreements and to force it to abandon them in the future. The word "Sanctio" in Latin means "instruction, order.
Sanctions can be imposed by a single country against a violating country, or by an entire bloc of countries, such as NATO or the EU.
Examples of sanctions:
Iran, which began a nuclear program that was far from peaceful, was subject to U.S. and EU sanctions, which included an asset freeze and a ban on Iranian oil imports. Russia, which took Crimea from Ukraine, was sanctioned by Western countries and Japan.