Can only Java language help you build android apps?

Question

Java

Answer 1

No.
You can build Android apps using C#. Xamarin

Also you can build hybrid App using frameworks such as Ionic, Cordova, and the likes.

Hybrid App Dev allows you to build Apps using HTML, CSS & JS and deploy on various platforms (Android, IOS, Blackberry...)

I hope this answers your question

Answer 2

Kotlin also is fully supported by Google at this point. as I understand it, most languages have tools to make android apps. C#, C++, Python, etc