Electronic things work because of electricity that's transmitted using tiny parts. The keyboard you play in your band is electronic, and so is the calculator you use in math class.
The adjective electronic describes machines and devices that require electrical currents to run, and that use microchips and transistors to direct that current. There are electronic parts in many areas of our lives — cars use electronic devices, and so do computers, radios, televisions, and cell phones. Electronic instruments like synthesizers have lead to an entire genre of music that's also known as electronic. The word itself was first used in the 1930's to mean "pertaining to electrons."