Not to be confused with Music groups or other groups. This explains it. Makes your Echo more room and location smart.
“Once you’ve added your devices, it helps to organize them and your smart speaker(s) into groups based on where they are in your home. If you create a Living Room group and add the Alexa speaker and smart lights in that room, you’ll be able to say “Alexa, turn on the lights” instead of “Alexa, turn on the living room lights.” It’s not a huge difference, but it makes the voice commands feel much more natural.”