Travertine is a stone that comes in many different finishes. Travertine comes filled and unfilled; this means that travertine naturally has holes that run throughout the stone. The filled travertine is exactly as you would expect: the holes are filled, giving the stone a smooth finish.
Travertine comes in a honed (matte finish) and a polished finish. These finishes need to be cared for and will from time to time need honing to remove scratches and etching, or it will need to be re-polished and sealed.