The moon is +/-240,000 miles away. Speed of light is +/-186,000 miles per second.

240/186 = 1.29 seconds from earth to moon, then another 1.29 seconds back.

• Note, this is crayola level precision, which is suitable for conversation. Additional considerations are that radio waves move slower throigh earths atmosphere and will add a few fractions of a second. Also adding in delay will be signal processing (voice to radio wave and radio wave to voice) on each end. Without doing the math, I'd swag 1.5s as the functional delay and would accept an Acktually statement from someone who's more conversant somewhere around either answer.