When a reflection over the x-axis is made:
• The x-coordinate of the reflected point stays the same
,
• The y-coordinate of the reflected point changes sign.
So what we look when we see the coordinates of the reflections over the x-axis is that the points are in the same place in x, but in the opposite place is y.
The general rule can be writen as follows:

x is the same after the reflection, but y changes of sign.