To solve for what the equation of a line is given the conditions in the question, let's put it in y=mx+b form so we can find the actual answer. First we need to fill in what m is. Because slope or m is 0, the part of the equation looks like this y=0x+b. 0 multiplied to anything is just 0. So it becomes y=0+b= y=b. Fill in what b is. Remember b is the y intercept the point they have given you in the question. So y=b becomes y=-2. The equation of the line is y=-2.