Google AdWords lets you prevent your charity's ads from showing for searches conducted in certain countries or by people who speak a certain language (users can set their language preferences on Google and if they use a different version of Google eg. Google France, their language preferences will automatically be set for the national language).
There is no point in showing your charity's ad to people who won't understand it. If you need to reach people that speak different languages, create separate ads for each language. Likewise, if you only sell products to one country, or can only accept local volunteers, then limit the number of countries where your ad is shown. Otherwise people from other countries may click your ad, which is a waste of money.