The plugin has automatically support for the language of the buttons on the map. It takes the language setting of the site and will give this language to the Google Maps API script. So if your site is in german, the buttons on the map will also be in german.

In the configuration of the plugin you can choose the following configuration:

• Site then it will take the language defined in Joomla (and Joomfish for 1.5.x)
• Config then you can set the language in the next field
• Joomfish then it will use the language set byJoomfish (Only for Joomla 1.0.x)
  
• Use then it will use the language that the user has set in his browser.

Check if your language is available at: Support languages Google Map API

To change the language of the buttons and link outside of the map you have to change the fields in the configuration of the plugin. The labels can be made depended by the language by entering in the fields for labels:
en;Goto
nl;Ga naar
de;Route berechnen

Place each language on a new line!

There is also a text for if a user has switch off javascript support. This is the php constant _CMN_JAVASCRIPT. This constant is in Joomla 1.5 placed in the language directory in file en-GB.plg_content_plugin_googlemap2.ini. You can make your onw language file based on the iso-code for the plugin and give it your own text.