It's very nice to hear that you have the ambitious to advance your career in business. I agree with Steve that if you can speak English, basically, it's very easy for you to go around the world in Science and business.
I will say your territory decides the language you need. If you will have a lot of business connection in Japan, Korea, or China, it will be very helpful that you can speak their language. I grow up with Malay, English and Chinese. It makes me very comfortable when I moved to Taiwan, as I can speak Chinese. When I moved to Japan, I started to learn Japanese. Fortunately, their are from the same root, my native language (Chinese) speed up the process of learning Japanese.
My suggestion is, you can choose to learn a third language that you like. Ideally, Japanese or Chinese, as you already know Spanish, it is more easy to adapt to European language, while learning Japanese and Chinese will take you a much longer time.
Last updated Nov 28 '17 at 20:08