This file includes all Google Material icons in one gigantic Artboard. The icons are organized in categories with descriptions. Unfortunately, the actual icons are all named as Shapes.
Nevertheless, this is a great resource and here is a tip for searching and finding icon layers quickly. Let's assume that you are looking for a hotel icon. You can filter all layers (⌘ + F) and type "hotel", then you can click on the text layer and use Sketch's Zoom Selection shortcut (⌘ + 2) in order to zoom to the selected layer.