English is long established as the international language- many people are now more or less capable, no matter where it is in the world, to communicate with others using English. "How well"- that is the real question!
Many people learn a foreign language at some point in their lives. Maybe you are learning a language right now? A common question language learners have is - "How do I learn a new language most effectively?" Another is "What's the most effective learning method?"