Then there's this: A Northwestern University study says bilinguals process information more efficiently and easily than monolinguals. If your business constantly runs on tight deadlines, you might want to consider how helpful that particular skill can be. Another study, this one from the National Institute of Health, says bilinguals often perform better on tasks which require conflict management.

A different study says knowing a foreign language reduces heuristic biases in decision making. That could lead to better business choices, something that's always in demand.

The report points out employees endowed with objectivity and mental sharpness are viewed as assets to their employers, and adds many businesses spend a considerable sum to recruit bilinguals when they realize they need them. It suggests employers consider learning a second language as professional development, and invest the money in workers who are already with them and know their business.

Even if you have to provide an incentive to get these employees to commit to study, you'll also be letting them know you value them enough to invest in them. The report says this “is good for their productivity, which ultimately makes it good for your business.”