A lot of CB's are standard 40 channel radios. Some, though, have Upper side band and lower side band. Also sometimes called hi and low. So every channel has 3 bands. such as, channel 1 low, channel 1 normal, and channel high. The side bands have to be "dialed in using a clairifier knob on the radio to make the speech understandable. Perhaps this is what he meant. Find your local CB radio dealer and he can show you the difference.

God bless