If you want to start using Kotlin for Android development, read Google's recommendation for getting started with Kotlin on Android.
If you're new to Android and want to learn to create applications with Kotlin, check out this Udacity course.
Ans.
Kotlin is a strong programming language, and it usually takes around four weeks to get a good start with it.
Learn Kotlin
Kotlin is easy to learn, especially if you already know Java (it is 100% compatible with Java).
Kotlin is used to develop Android apps, server side apps, and much more.