Answer:
The signal is the function which that carry information about the particular phenomenon in the signal processing. A signal is also define as the change in the quantity which is observable.
In terms of telecommunication, a signal is the varying current, voltage and the electromagnetic wave which basically carries data or information. Signal can be in the form of audio, image and radar related.
A signal can be used be various signal processing system and telecommunication fr the transmission of information from one device to another device.