The inverted triangle represents our yield sign. Yield means you must give the right of way to other road users. Yield signs also mean that a driver may proceed without stopping - provided that it is safe to do so. Less common to see is a regular triangle shape with the same configuration of colors as the yield sign. When this sign is displayed it means ‘caution’. Drivers may see the upside-down yield sign when vehicles break down on the side of a road.

Source: Valley Driving School