The equation is y= -2.
How? If you recall, a linear equation is y= mx+b. The m is the slope (growth) and b is the y-intercept ( where the line crosses the y-axis).
Now since there is no slope or m, the equation would look like this:
y= b or y= 0+b
Next, you want to input the coordinator points (0, -2) into the equation. reminder: (x, y) = x=0 y= -2
y= 0+ -2
y= -2
And there you go! The equation is y= -2. I hope I help you in solving this problem, if not message me, because I'll be glad to help you.