1. Find the number 5 on the horizontal line identified by x at its right end. There is a vertical grid line through that point. Count the number of times the circle touches or crosses that vertical line at x=5. (It's a short count: 1 touch.)
Since the touch (point of intersection with x=5) is on the x-axis, the y-value at that point is zero (0). There is 1 output value and it is 0.
2. Find the number 2 on the x-axis and count how many times the circle crosses the vertical line through x=2. There are two (2) of them. One of the crossing points is 3 squares above the x-axis, so has the output value y=3. The other crossing point is 3 squares below the x-axis, so has the output value y=-3.
There are 2 output values, and they are +3 and -3.
3. The relation shown in the graph is NOT a function because a function is only allowed to have one output value for any value of x. We say this graph "fails the vertical line test" because you can draw a vertical line that intersects the graph in more than one place. (The line x=2 is one such line.)