Radio waves travel at the speed of light; it takes 1¼ seconds to cover Earth-Moon distance. It is the reason in the Apollo missions after Houston says something, the response from the astronauts on the Moon will arrive only after 2½ seconds.
Some presentations of the Apollo missions are edited to cut out the gaps created by the delay, and flat-Earthers use them to dismiss the Apollo missions as fake. However, in the actual audio recordings and the transcripts, the delays are there.