What is the meaning of reverse sanctions

In essence, sanctions against Iran (or any nation) imposed by another nation or group of nations (such as the USA or the UN) are economic in nature. Sanctions are essentially meant as a mild form of punishment against a country's government, though they always wind up affecting the populous. Take the Gaza Strip, for example: Israel is tired of dealing with the rockets being launched into Israel, tired of the terrorism. So because they know that Gaza Strip needs building materials to rebuild vast parts of their cities and because they need electricity, Israel has imposed sanctions on Gaza, militarily enforced, for those things. So Gazans can't build anything, repair anything, and it's even hard to have stable electricity.

As for Iran... In general sanctions may include embargoes against it on US or UN-nations imports, which could cut off their supply of grains or textiles or lumber or steel or ore, or raw materials, or whatever it is that they are trying to import because they don't have. Could be anything that Iran, unable to make for itself or unable to get because they don't have the resources, needs from outside of its borders. Though sanctions are officially meant for the governements of various nations, they almost always affect the populous, which causes civil unrest. Ultimately the civil unrest, in an ideal situation, puts enough pressure on the government of the country being sanctioned that the government reverses whatever policy it enacted that caused the imposition of sanctions to begin with.

The goal of sanctions is to squeeze another country economically so that they will relent over whatever policy they have that is making other nations mad. In Iran's case, the UN is imposing sanctions to try to squeeze them into dropping their program for weapons-grade nuclear enrichment. The fear of many nations is that if Iran gets its hands on a nuclear weapon, it will destabilize the Middle East. Considering their president has publicly stated he wished Israel were "wiped off the map", and that Iranian mercenaries are trying to destabilize Iraq, the fears are well-founded.