The Light Manager window lists every light in the scene and lets you control a number of attributes for each of them. It is available from the Arnold menu - Arnold> Utilities> Light Manager or from the Arnold shelf. It is a convenient way of handling lighting.
Creates a light based on the selection. Choose between directional light, point light, spot light, Maya area light, Arnold area light, SkyDome light, IES light and Mesh light.
Clicking on the light icon will select the light in the Maya viewport.
Displays the name of the light.
Gives you the option to adjust the color of the light or connect a texture map.
Allows you to adjust the brightness of the light.
Allows you to adjust the intensity of the light in exposure units. Increasing the exposure by +1 doubles the amount of light.
Allows you to adjust the sampling quality.
A toggle for enabling/disabling the visibility of the light in Maya.