This question is a bit tricky because it mixes units in a way that doesn't make sense. Here's why:

* Kilometer (km): A unit of distance.

* Second (s): A unit of time.

Light travels a certain distance in a certain amount of time. We usually express this as the speed of light:

* Speed of light (c) = 299,792,458 meters per second (m/s)

To answer your question correctly, you need to ask:

* How far can light travel in one second? The answer is approximately 299,792,458 meters (or about 300,000 km).

Let me know if you have any other questions about light or speed!