All content available on Codewars is created by members of the Codewars community. It's ideas of Codewars users that get turned into kata, and the fact that users are familiar with plenty of programming languages allows for a large number of available translations.
This section of the documentation is meant mostly for authors and translators who would like to introduce new challenges and make them available for other Codewars users. Creating a kata or translating it, even an easy one, is a difficult task. It requires a much wider set of skills compared to that of just solving a kata. Unlike problem solvers, authors need to master skills related to software development in general, as well as problem design, writing good test suites, documenting the task and its requirements, and communicating with reviewers.
To support users in creating good quality kata and translations, a set of help pages were created with articles related to content authoring activities: tutorials explaining how to create and translate a kata, and a reference of guidelines and requirements that every author should follow to make sure that a piece of content created by them meets quality criteria.
For more details, see help pages related to creating a specific type of content: