As WordPress is a free and open source project, it is built and maintained by a community of volunteers. These volunteers contribute code, write documentation, provide support for people, organize WordCamps, and do a lot more behind the scenes to help keep WordPress running and updated.
Siobhan McKeown has written an excellent article on contributing to WordPress. It is a pretty long read but it’s worth your time and highly informative. Make sure you are going through all the points mentioned in the article.