utilizing electronic principals, how does a jamming device operate?

Answer 1

generates radio waves at a wide range of frequencies. This drowns whatever signal is being jammed.

Answer 2

At its simplest, a jamming device radiates a signal on the same frequency as the intended signal. By providing a stonger relative signal AT THE RECEIVER than the intended signal, the jammer will capture the receiver, in the case of FM; the receiver will hear the jamming device, not the intended transmitter.