Explanation:
We flip the sign of the x coordinate from -1 to +1 when reflecting over the y axis. The y coordinate stays the same.
This is one way to write out the steps:
[tex](x,y) \to (-x,y)\\\\(-1,4) \to (-(-1),4)\\\\(-1,4) \to (1,4)\\\\[/tex]
The graph is below.