Most maps you see of COVID-19 show things by raw numbers, but that isn't a very good way to look at things. Some countries, like China, may have large raw numbers, but with only a small percent of the population affected. Conversely, some small countries, like Iceland, may have small raw numbers, but with a very high percent of the population affected, relatively speaking.
To compare countries more fairly, the values can be normalized by population.
Looked at it in this way, you can see that your chance of contracting COVID-19 is much higher in a place like Iceland than it is in China. In fact, you are very unlikely to contract COVID-19 in China, despite the large raw numbers there.
The maps on this site show the countries and states colored by cases per million people. The more cases per million people, the darker the color. If a country has no data, it is displayed as grey. You can hover over or click countries/states to see the numbers.
The maps use the same scale, so you can compare US states with countries of the world.
There's a maximum cases-per-million used in the charts, which is currently 10,000. This will likely be increased in the future, as more places exceed this value. In the beginning, it was 5,000. For deaths, the maximum is 400 deaths-per-million.
If the cases-per-million is over the maximum, that country's cases-per-million will not be displayed. The reason is that there are some tiny countries that are outliers, like Vatican City, and these will set the scale so high that it will be hard to see the other countries. If you are really curious about the small countries, you can visit Worldometers' coronavirus page and sort by "Tot Cases / 1M pop".