French

The Most Practical Foreign Language While any language will be useful for some jobs or for some regions French language is the second most frequently taught language in the world after English. The International Organization of Francophonie has 56 member states and governments. Of these, 28 countries have French as an official language. French is the only language other than English spoken on five continents. French and English are the only two global languages.

French, along with English, is the official working language for example:

the United Nations
UNESCO

For the students and researchers who know French have access to these works for several years before they are translated into English. Many significant works are never translated and remain accessible only to those who know the language. In addition, most graduate schools require knowledge of at least one foreign language, and French remains the most commonly used language after English.

In sum, French is the language of the future.