It is natural to compare Kotlin to Java. Both Kotlin and Java are object-oriented programming languages that run on the Java Virtual Machine (JVM). Further, it is compatible with existing Java code.
Kotlin is the programming language for server-side and Android development; while Java is the preferred language to develop enterprise applications. Further, it is the Google recommended programming language for building Android apps. In other words, if you are building an Android application from scratch, use Kotlin.
Further comparing the two, one of the things in the Kotlin programming language that Java does not have is extension functions. There is also null safety and data classes. You cannot assign a null value to any variable or object.
A pro for Kotlin is since there is much less boilerplate code, you should be able to write half the Kotlin code as you would if you were programming in Java. A con of Kotlin is its compilation time is slow.
If you are interested in learning to code Kotlin, you may want to consider the Kotlin Bootcamp for Beginners. During that bootcamp you will learn the basics of Kotlin as you create various programs in Intellij IDEA.