Explanation:
I assume the grid units are single units (1, 2, 3, ...).
to be a function every value of x must have exactly one value of y.
but that is violated at x = 2. at that point y can be either +3 or -3 (indicated by the 2 points at x=2).
so, no, it is not a function.
the domain is the interval or set of all valid x (input) values.
since we have no continuous curve but single points, it is a set :
x € {-4, -3, -2, 1, 2, 3, 6}
the range is the interval or set of all valid y (function result) values. again, it is a set for the same reasons :
y € {-3, -2, 0, 1, 3, 4}