Questions that are only about Kali Linux and not about Ubuntu are off-topic here! Please ask them on Unix & Linux Q&A.
Kali Linux is a Linux distribution based on Debian. It is often used for security testing and comes with a huge set of tools for that. It is not a general-purpose Linux desktop distribution.
Kali Linux is a Linux distribution based on Debian that is designed to be used specifically for information security work.
Per this post on Ask Ubuntu Meta, questions that aren't about Ubuntu or official derivatives are off topic and should not be asked here; rather, they should be asked on Unix & Linux. The tag reference for Unix and Linux Q&A is kali-linux.
Here is the documentation, for the curious.