System Linux is a collection of software additions to the Arch Linux repositories.
The default selection is for the development of KDE and Plasma C++ software.
It is not for beginners. If you have no experience with Arch Linux, it is highly recommended that you start there or with LFS.
The System installer allows for selecting groups of software such as Desktop Environments, Programming Language Setups and various third-party Arch Linux repositories such as BlackArch or ArchLinuxCN.
This method allows a quick and easy setup for a given use case without having to dig through wiki pages or remember package group names or repository URLs.