Answer:
The graph of the line x = 12 is a vertical line.
A vertical line is a line with a constant x-value, in this case x = 12, so all the points on the line will have an x-coordinate of 12, regardless of their y-coordinate. All the point on the line will have the same x-coordinate and it will be parallel to the y-axis.
It does not have a slope, does not cross the y-axis, it is not horizontal.