To reflect a point across the x-axis, you change the sign of the y-coordinate while keeping the x-coordinate the same.
Given the point \((-5, 10)\):
- The x-coordinate remains the same: \(-5\)
- The y-coordinate changes sign: \(10\) becomes \(-10\)
Therefore, the reflection of the point \((-5, 10)\) across the x-axis is \((-5, -10)\).