English is one thing - knowing it enables access to a vast body of knowledge which is not translated to your native language, but you can - in principle - be a competent developer without ever learning English. It will be harder because you'll have a lot fewer books, articles, talks, blog posts and so on to read and listen to, but it's possible.

Writing is another thing. In my opinion, you cannot be a competent programmer if you are unable to communicate well in writing.