The equation "y = 5" represents a horizontal line on a graph where the value of y is always 5, regardless of the value of x. This means that for every point on this line, the y-coordinate will remain constant at 5, while the x-coordinate can vary freely. In a coordinate system, this line intersects the y-axis at the point (0, 5). It indicates that no matter what value you choose for x, the output will always be 5. This concept is fundamental in algebra and helps in understanding linear relationships.