The word "GATT" stands for the General Agreement on Tariffs and Trade. It is a noun and refers to an international organization that was created to help countries work together on trade. The main goal of GATT was to promote trade by reducing taxes on imports (called tariffs) and limits on how much of a product could be brought into a country (called import quotas).
GATT was an important organization that helped countries trade by reducing tariffs and quotas.