@tschrenk this system uses an Amazon Echo to capture a voice command from a user. Alexa then triggers a custom applet that connects through the IFTTT service to send a signal to the little microcontroller which then acts like a switch. It should be compatible with most devices that have the 3.5 mm jack input. There is a limit to how much current the microcontroller can handle, so it may not work with heavy duty switch adapted toys, for example.
This could be combined with a suitable switch outlet adapter (e.g. [AbleNet Powerlink](https://www.ablenetinc.com/powerlink-4-north-america)) to control a 120V appliance, fan, etc, though there are less expensive ways to do that. (Like an Alexa-compatible Wi-Fi enabled plug @MMC_Milad mentioned above)
Instead of using an Amazon Echo / Alexa, this could also be used with a different IFTTT trigger. There are ton of different things that can be used to trigger an action on IFTTT (e.g. SMS, email, date/time, Twitter, etc, etc). Note that IFTTT recently changed their pricing; the free version now only allows 3 applets.
Hope that helps.