The range of the plotted function is the set of y values that it takes on. The curve is continuous and ranges from y = -2 (at the leftmost point (-11, -2)) up to y = 10 (at the rightmost point (11, 10)).
However, the unfilled circle at the left endpoint means that y = -2 is not actually included in the range.
So the range in this case is -2 < y ≤ 10. (note the strict inequality on the left)