If you are trying your hands on android development go with Dart because it gives you cross platform flexibility.
Code ones run everywhere.
Dart is very simple to start with and learning curve is easy. Lots of library are available to help faster development curve and look is very native like as it provides 60fps performance.
As a fresher when you want to start Android developement you should have to learn first basic of android. Then you can go with Dart to learn CrosPlatform App developement with Flutter. Flutter is the future trending framwork to develope applications for web,Mobile, windows, mac... But Before start with Flutter You should have basics of Android app development with Android studio. If you want to develop ios App, should start basic developement with XCode.