Note that the line is a horizontal line, passing through the point (0, 1) in the y-axis.
All points of this line have 1 as their y-coordinate. That is, this line contains points like (-3, 1), (-1, 1), (5, 1), (17, 1)... etc.
Thus, this is the line where y is always 1, this is the line y=1.
Answer: y=1