Just like you visit maps.google.com.tw or maps.google.co.kr or maps.google.co.jp, you can see their own language shown on every country. I
maps.google.com.tw
maps.google.co.kr
maps.google.co.jp
In Google Maps v3, you can use the "language" parameter:
Language codes list: https://developers.google.com/maps/faq#languagesupport
More info: http://googlegeodevelopers.blogspot.com/2009/10/maps-api-v3-now-speaks-your-language.html