As can be seen in the figure attached, -19 is located on the left of -16.
Every point of a number line is assumed to correspond to a real number, and every real number to a point. So as we love leftwards on the number line, the values keep on decreasing. Similarly while moving rightwards on the number line, the values keep on increasing.
So, because it is known that -19 < -16,
-19 is located on the left of -16.