To calculate the slope \( m \) of a line that passes through two points \((x_1, y_1)\) and \((x_2, y_2)\), we use the formula:
\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]
In this case, we have the points \((6, -5)\) and \((-6, -5)\). We can assign:
- \((x_1, y_1) = (6, -5)\)
- \((x_2, y_2) = (-6, -5)\)
Now, substituting these values into the slope formula:
\[ m = \frac{-5 - (-5)}{-6 - 6} \]
Calculating the values:
\[ m = \frac{-5 + 5}{-6 - 6} = \frac{0}{-12} \]
Since the numerator is 0, the slope \( m \) becomes:
\[ m = 0 \]
This indicates that the line is horizontal. Therefore, the slope of the line that passes through the points \((6, -5)\) and \((-6, -5)\) is
\[ \boxed{0} \]