In general, Android app development is divided into multiple parts, including frontend development. It is a process of creating an interface that allows users to view data and take actions.
It is the first part of android app development, it includes topics that are necessary to build a static working app (Static apps display fixed information and don't communicate with any server).
All subtopics of the android frontend are also considered fundamental to android development so learning all the subtopics can you help you build complex apps.