Each scale div. on the vert. axis represents 4 units. Starting with the 8 shown, count your way down the vert. axis: 8, 4, 0, -4, -8 (and so on).
Each scale div. on the horiz. axis represents 4 units. Count your way up, starting from -12: -12, -8, -4, 0, 4, 8, 12, 14, and so on.
