Perhaps you are referring to the vara, which was a surveying unit of length, originating from Spain. It is approximately 1 yard. Many surveys in Texas were specified in vara, which was 33 1/3 inches. Note that the var or vara is a unit of length, while acre is a unit of area. So square vars could convert to acres. See related link, below.
1 metre = 1.0936 var (yards).
1 var means how many sq ft?
1 square VAR = 7.7 Square feet
1.196 var, approx.
One var equal to how many feet
1
1 acre = 4,046.8564 square meters
60.5 cottahs = 1 Acre
1 acre = 43,560 square feet
1 acre = 4,046.86 m2
1 acre = 43,560 square feet.
Answer: 1 acre = 0.004046 km²