If you are outside the US, it's a country ranking.

By default, the app shows your rank within your state (if in the US, not sure what subdivision it will show for other areas of the world). But if you click on the Everyone tab, then you'll see the top 50 Wazers on your server, and at the bottom (if you are not in the top 50), you'll be listed with your rank against "everyone". You can click the State bubble if you want to see the top 50 people in your state, and you'll be shown with your rank in your state.

Your Waze driver level is based on your rank against the other drivers in your state (after the first level bump for driving 100 miles), you move up in ranks when reach top 10%, top 4%, and top 1% of wazers in your state.