Question

What how many miles or yards or feet is 6 acres

Answer 1

You would have to take 43,500 x 6 which equals 261,360 sqft. 

Answer 2

'Mile', 'yard', and 'foot' are measures of length or distance.
'Acre' is a measure of area.  So they're not equivalent units.

1 Acre = 43,560 square feet, 
               4,840 square yards,
               0.0015625 square mile .

6 Acres = 261,360 square feet,
                 29,040 square yards,
                   0.009375 square mile.