The square yard is a unit of area and is an imperial unit with the symbol ya².
One square yard is equal in area to a square with edges one yard in length. It also equals 1,296 in² and ≈ 0.836 m².
The square yard is a common unit of measurement in the UK and US.
The hectare is a unit of area and is a non-SI but metric unit with the symbol ha.
It represents the area equal to that of a square with edges 100m long (ie 1hm² or 10,000m²). This is the equivalent to about 2.47 acres.
Its size is down to its use primary use; that for measuring the size of land.