The comment box is correct ...
Any graph shows the variation in two quantities with respect to each other. The area under the curve is found from multiplying the value on the y-axis by that on the x-axis, therefore the units are found from multiplying them together.
As stated, the units for the area are thus
This tells you that the area under the graph is the displacement from the origin (not quite the same as distance travelled., but that's another story.)