First let us, find what is a signal , about which we are talking.
Signals usually in electrical engineering is a function that conveys some information.
Examples of signal include :
"signal" includes audio, video, speech, image, communication, geophysical, sonar, radar, medical and musical signals
What is analog signal ?
Analog refers to circuits in which quantities / attributes (for example : such as voltage or current ) vary or change at a continuous rate.
Can be used in analog devices only. Best suited for audio and video transmission.
At the same time ,digital signals :
In digital electronics, quantities are counted rather than measured.
Best suited for Computing and digital electronics.