You might take for granted that you can just open Google Maps and see what traffic is like, but that feature isn't available everywhere. There are still numerous countries that don't have live traffic, but today ten more of them do. Google has updated its support docs to call out the newly added markets, but not all of them will get the same features.
Here are all ten countries that now offer the traffic layer in Maps.
According to Google's table, the first nine have full support for live traffic with "good data quality or availability". Vietnam has the traffic layer, but it only offers "approximate data quality or availability." So, it'll work, but not as well as it does in other countries that have the feature.