cPanel is a Linux-based web hosting control panel that provides a graphical interface and automation tools designed to simplify the process of hosting a web site. cPanel utilizes a 3 tier structure that provides capabilities for administrators, resellers, and end-user website owners to control the various aspects of website and server administration through a standard web browser.
If you do not know and not understand?
https://en.wikipedia.org/wiki/CPanel
Yes. You can. Open the file Manager in CPanel and changing the code files or adding new files you can change practically everything.