What does the yellow light on the rim of my echo dot mean?

That light means the Echo Dot is trying to connect to a network.

Its for notifications, the yellow light is the notification light you can disable the lights by putting the device in do not disturb mode,,just speak into the device say ok alexia do not disturb,to turn notifications back on just speak into the device say ok alexia you can disturb me..if there any thing else you need it can be purchased here>>>www.discountbargainprices.com