Why is Alexa flashing yellow, green, etc!?
Since your Echo speaker doesn’t have a screen, it uses a light ring to provide visual feedback. Even the screen-equipped Echo Show has a small light band that also uses this feedback method.
Light codes are great in principle, but if you don’t know what the lights mean it’s nothing more than something pretty to look at. The good news is that there aren’t too many of these light codes and most of them have fairly benign meanings.
See this handy index below that will explain what the different colors can mean.