WHAT IS XPOSED Installer FRAMEWORK - Alternative( Magisk ) :
Xposed Framework is a framework for your rooted Android phone. It in itself does not do much. But it lets you install other apps/mods/tweak with system level functionality without having to flash them via custom recovery.

Xposed Framework makes it a lot easier to customize/mod your phone. Not only can you change the looks of your Android phone but also increase its performance and tweak system level functionality with Xposed Framework.