The equation "x + y = 5" represents a linear relationship between two variables, x and y. In this equation, the sum of x and y equals 5. This means that for any value of x, there is a corresponding value of y that will satisfy the equation. For example, if x is 2, then y must be 3, since 2 + 3 = 5. This equation can be visualized as a straight line on a graph, where the x-axis represents x and the y-axis represents y. The line will intersect the axes at the points (5, 0) and (0, 5). Each point on this line represents a unique pair of values for x and y that add up to 5.