Put simply, satellite transmission is a relay of information between a satellite and a communication point back on earth. To understand this fully, however, I'll need to explain in a little more depth.
Ultimately, a satellite is an object that manoeuvres itself in a circular orbit around a planet. A great example of a satellite is the moon as it orbits around the earth.
There are, however, non-natural satellites that we've sent into space for purposes such as providing information for our satellite navigation systems.
What is satellite transmission?
When our man made satellites have recovered information that's useful to us back on earth the send, or transmit, that information back to a communication centre on earth.
For example, if a new road has been created, a satellite will transmit this information back to earth so your satellite navigation system can be updated with the location of the new road.
Overall, satellite transmission is the sending and receiving of information between a man made satellite and a communication tower back on earth.