How can I implement AdMob on Raylib? On the screen or just open ads whn click a button (to don't bother players)

Admob isn't Java and Raylib C++?

I know exist NDK but it's easy to implement?

I haven't tried it but I think you can try with Firebase C++ SDK: https://firebase.google.com/docs/admob/cpp/cocos2d-x

Documentation is for Cocos2d-x but it should be similar with raylib.