The Full Form of AAPT is Android Asset Packaging Tool.

AAPT2 (Android Asset Packaging Tool) is a build tool that Android Studio and Android Gradle Plugin use to compile and package your app’s resources. AAPT2 parses, indexes, and compiles the resources into a binary format that is optimized for the Android platform.

Android Gradle Plugin 3.0.0 and higher enable AAPT2 by default, and you typically won’t need to invoke aapt2 yourself. However, if you prefer to use your terminal and your own build system over Android Studio, you can use AAPT2 from the command line. You can also debug build errors related to AAPT2 from the command line. To do so, you can find AAPT2 as a standalone tool in Android SDK Build Tools 26.0.2 and higher.