Which programming language is most important for learning hacking or cybersecurity?

Answer 1

In web, javascript can be used as hacking language.
In addition to this, python, SQL and php are among the top 5 hacking languages and also help in cybersecurity.

There are many courses like ethical hacking, cybersecurity and many others which can help you.

Answer 2

Python, C, ruby

Answer 3

hacking is very general.
for cybersecurity you should know about SQL, PHP and JavaScript (optionally).
If interested on 'malware analysis' as many named it (cracking auth, reverse engineering executables, breaking encryptions eg: find and deofuscate AES key from a executable), it depends on the language the application created. For applications create in C# you just have to know only C#, for C/C++ you should know C/C++ but also need at least a basic knowledge with assembly in many cases