"Distance" here is the total distance traveled along the red path (see attached) from point A to point B. Just count how many how sides of each square in the grid are touched by the path. Then distance = 24 units.
"Displacement" is the net distance covered by moving from point A to point B, or the length of the green path. So displacement = 2 units to the right. Of course, your question seems to ask for the displacement in terms of units to the left, in which you could say -2 units to the left.
