In the HackerRank Coding Tests, the languages option available in the editor lists the different programming languages you can choose from to write your solution. The editor automatically resets and adapts according to the chosen language.
Typically, the test setter at your hiring company determines the programming languages which will be allowed to answer a particular coding problem. This is generally based on the specific skills the company intends to assess in each Candidate. Only the permitted programming languages are available for you to choose from and write your solution.
Example: In your HackerRank Test, assuming you are at a coding question which requires you to write the logic to find the first non-repeated character in a string. Your test setter may want to assess your coding skills in C# and Python, and hence, the languages option lists only the C# and Python languages to choose from.