The next icon, which looks like three layers with an arrowhead pointing downward, is for the layer isolate command. This command will let you hide all the layers of the drawing except your selected layers:

To use this tool, click on its icon or use its command alias, LAYISO. Now click on the objects of the layer that you want to isolate and, once you have made your selection, press Enter. All the layers in the drawing will be hidden except your selected layers and the objects on the selected layers.

As an example, for this drawing, I will click on one of the walls and a door and press Enter. The final result in my case looks like the drawing shown here:

To "de-isolate" the layers and bring all layers back into the drawing, just select the icon right underneath the first icon on the second row of the Layers panel. When you click this icon, all the layers will turn on and objects on those layers will show up again in the drawing.