In terms of your connected home devices, there are just three basic commands you can say to echo: on, off, and dim.
Echo will accept a number of natural language variations of those. So you can say “turn on the hallway,” “turn hallway on,” “Switch on hallway,” etc. but that’s about it.
The only device classes that echo can control are lights, switches, and dimmable lights.
However, by using virtual switches, you can then get echo control of pretty much anything in the smartthings network because you can tie the virtual switch to a change in mode, or to a hello home action, or to a smartapp.
But The spoken commands to echo are all variations of on, off, and dim.