You can see that the function is a transformation of the core function , which is a standard parabola with the vertex at the origin. The function is identical, but flipped about the x-axis. Are you familar with the equation:

??

In the graph we can see:

a=-1, h=-2, k=4

Do you understand this. The parabola is flipped around the x-axis, shifted two units to the right, and 4 units up.