A translation has occurred when an image slides all points of it's figure the same distance in the same direction. A translation occurs when a figure moves along a vector where each vertex and its image move the same distance and are parallel to the vector (same distance). You could identify that this is a translation because there is a vector that describes the translate . If you did not have a grid you could still identify that this is a translation because there is a vector and each vertex of the image is moving in the same direction and the same distance. This is a translation and not a reflecting over the y-axis because the points did not move equidistance from the y-axis. Therefore, this rigid motion is an example of a translation and not a reflection over the y-axis.