This icon is a part of a collection of Światło wyłączone flat icons produced by Icons8. Icons follow the guidelines of iOS, Windows, and Android and are designed by a single designer, guaranteeing the consistent quality. Both PNG and vector are available.
This is a lightbulb indication to show that the light is turned off. It shows a lightbulb, with a large bulbous circle at the top which tapers off onto the bottom, and there's a large X in the middle to indicate the light is off.