If the line is parallel to the x-axis then it is a horizontal line with slope 0. These lines have form y=b where b is the y-intercept or y value of all points. y=-3 is the line since (2,-3) is on the line.
You just have to answer to all of the questions and bullet points. Think about them, and do some sketches. In the end that will help you to end the assignment.
