AdWords lets you choose the languages of the websites that your ads appear on. You can choose to target specific languages or all available languages for greatest reach.
To determine if you should target multiple languages, consider the following:
What languages do your customers speak or what languages are spoken in the areas you'll target?
Is your website available in multiple languages?
Is your business, such as your customer support and sales teams, equipped to handle inquiries from multiple languages?
AdWords decides where to show ads based on one of the following:
Google language setting. Each Google domain has a default (for example, Google.it defaults to Italian...