To calculate the area of a wall, you can use the formula for the area of a rectangle, which is given by
\[ \text{Area} = \text{height} \times \text{length}. \]
In this case, the height of the wall is \(6\) meters and the length is \(60\) meters. Plugging these values into the formula gives:
\[ \text{Area} = 6, \text{m} \times 60, \text{m} = 360, \text{m}^2. \]
Next, we need to convert the area from square meters to square miles. We know that:
1 square mile is equal to \(2,589,988\) square meters. Therefore, to convert square meters to square miles, we use the conversion factor:
\[ \text{Area in square miles} = \frac{\text{Area in square meters}}{2,589,988}. \]
We can now perform the conversion:
\[ \text{Area in square miles} = \frac{360}{2,589,988}. \]
Calculating this gives:
\[ \text{Area in square miles} \approx 0.000139. \]
Thus, the area of the wall, in square miles, is approximately
\[ \boxed{0.000139}. \]