Can you communicate at light speed?

Answer 1

Literally speaking, we do it every day, using the communications technique that we call 'radio'.
Information carried by radio travels from place to place at the "speed of light".

If you need an example of communication using nothing but visible light, then
you'd have to consider something like waving at a friend across the street.

But still, If we communicate through radio waves, to sound still takes time to reach our ears and get processed by the brain, taking up enough time.