Kotlin Beginner, how to become pro?

i am from database background having little knowledge on core java. i want to shift my career towards mobile development with Kotlin. Can you let me know from where to begin?

Best Regards,

start with the Kotlin-KOANS:

Thank you for your reply.
This link will helps on basics, how do i know the packages/functions used for building apps(camera,canvas,playing videos)?
i want to know all the packages ever created for kotlin, for developing apps with major functionalities with examples hopefully.

In the most of the times, I google for the name of the java-library and “kotlin”.
There are a bunch of libraries posted overhere: