"Light base" is probably just a name someone used for a light source component. These are made by a plugin for exporting to specific a rendering program. I see that you have icons for the Kerkythea export plugin. If you are using Kerkythea, then the yellow icons that look like Saturn and a cone are the ones that create a light source. I see other icons that look like rendering plugins as well. Depends on what rendering program you are using.