Answer
Refer to the image below for the graph.
Work Step by Step
RECALL:
The graph of the equation $y=k$ is a horizontal line.
Every point on the line has the same y-value.
Thus, to graph $y=0$, you can plot the points (-3, 0), (3, 0), and (3, 0), and then you can connect them using a line.
(Refer to the image in the answer part above.)