Knowing a different language is definitely beneficial to any career. I'm not sure it will necessarily translate directly into higher pay, but it will definitely open up more doors for you. It will also make you a much more valuable and versatile employee. If you want to open up doors that will allow you to work for a period of time in a different country then selecting a language in a country you'd be interested in visiting would be a start. In all cases, if you study a language, make sure you work towards being fluent. In order to make an impact and get roles that touch international teams you would have to have a proficiency in the language. Hope that helps.