Learning a second language allows you to be able to interact with millions of more people than you currently do. It also opens up numerous job opportunities, and enjoyments while travelling abroad. For me learning Spanish has really helped develop my sense of understanding for an entire culture as well. I would encourage everyone to learn a second language even just to challenge themselves.
If you are going to live in any country with a diverse population it's handy to have a mastery of atleast two of the popular languages. Here in the United States English and Spanish are the majority languages so those are the two I have a mastery of.
There are some amazing tools online that you use to learn a second language.