I'm not sure what you are wanting, buuuuuuuut reflecting over either axis means it's the same distance away from the axis but on the other side.
If you mean (2,3), the way we notate a point, to reflect over the x-axis is to make the y-coordinate opposite.
(2,-3)
What does that do? We are still the same horizontally but we've reflected vertically over the x-axis.
Want to reflect over the y-axis? That would stay the same vertically but be the same distance horizontally on the other side of the y-axis, so (-2,3) would be our new point.
