Translational motion of a molecule is the motion of the molecule along arbitrarily defined x, y and z axes. The translational energy of a molecule is only the kinetic energy.
Translational motion generally cannot be used by any spectroscopic techniques, but it is important as part of the overall motion of a molecule. Also, the kinetic energy - thus translational energy - a molecule has can be lost by emission of a photon, giving rise to emission spectra.
Click on the button to see molecular translation along the z axis.