"Electronic devices" are machines that use batteries such as laptop computers, phones, tablets, portable video games, and so on.
You can also use the word "device" by itself to talk about any machine:
I saw this device on TV that chops tomatoes perfectly in just a few seconds.
But more and more, "device" by itself specifically means a mobile phone or tablet computer:
I heard that they're releasing a new device at the end of this month.