If point (4, 5) is on the graph of a function, then the function must satisfy the equation f(4) = 5.
This means that when we input the value of 4 into the function, the output will be 5. In other words, the function, when applied to 4, gives us the y-coordinate of the point, which is 5. This is a fundamental property of functions represented graphically; any point (x, y) on the graph indicates that f(x) equals y.