Ha. According to the mathematical law, hectare is the unit of measurement, indicating the area, where Gong is the prefix of metric unit, indicating the metric unit in the international system of units, while Heqing is the ancient unit of area and one of the ancient land area units in China. In order to simplify the expression of measurement unit, the hectare is abbreviated as ha, where H stands for hecto, which means hundred, and A stands for are, which means area unit, so ha stands for area unit, which is equal to 100 hectares.