Kotlin interoperates with Java and its libraries, and is included with JetBrains' IntelliJ IDEA integrated development environment and Android Studio.

That’s important because if you want to target Android O, create an Instant App, start developing with Kotlin, or use the latest Android app performance tools, you’ll need Android Studio 3.0.

This is what libraries in Android Studio are for. They simply extend the capabilities of Java/Kotlin/the Android SDK by letting you use classes and methods built by other users.