Similar to how it operates in the world of Earth electrons flow between a negative and a positive potential. Remember that electric currents are usually transported through conductive wires. it doesn’t matter if these are enclosed by either air or a vacuum because the physical process is identical. Radio waves are able to travel the same (at greater frequencies and and often more efficiently) when in space than within an atmosphere. One of the main differences with Earth are that it’s much more difficult to eliminate waste heat in the absence of air currents, and there isn’t any sparking (because there isn’t any air to breakdown to conduct electrical energy).