According to the Economist, the Most Useful Language for English Speakers
So, you want to learn a second language to advance your career, but you don’t know which one will benefit you the most. If you asked an economist, they would probably answer you that way.
Emily Oster , associate professor of economics at Brown University, at Quartz, recommends two languages that will be of greatest benefit now and in the future . The first, Mandarin, is generally the most beneficial. It is the native language of 14% of the world’s population, many of whom do not speak English, which means it is the most influential language on Earth. It’s also incredibly important for business as native Chinese speakers are in high demand.
The second option, Spanish, has several distinct advantages. It is the second most spoken language on the planet and there are many native speakers here in the US, making it a rather valuable skill in your home country. It is believed that Spanish is much easier to learn than Mandarin, especially if the goal is fluency, so it is a more practical choice.
Of course, this is only one person, and your needs may call for something completely different. For example, if you do business in Germany, learning Chinese is probably not the best use of your time. However, this is interesting food for thought if you don’t know what to learn and are just trying to maximize your career potential with a single language skill.