The map icon button is called Map Layers and controls the ability to switch from one map view to another.
Below Layers is Center on Fleet. Clicking this icon adjusts the map to ensure that all vehicles are now in view. The more the vehicles spread out from each other, the farther out the map will zoom when this option is selected.
The plus and minus buttons will allow you to manually adjust your zoom. In addition to these buttons, the click wheel on a mouse will also change the zoom level.
This is Google Maps and Pegman is available for Streetview access.