Which language is the best one to learn to make a app?

Answer 1

Hello, Rafael Ponte !
Under Javascript, I highlight the following libraries:

PhoneGap is a free open-source framework for creating mobile applications created by Nitobi Software. Allows you to create applications for mobile devices using JavaScript, HTML5 and CSS3 without knowledge of "native" programming languages ​​(for example, Objective-C) and for all mobile operating systems (iOS, Android, Bada, etc.)

ReactNative - development from Facebook, which allows you to write under all existing platforms. The main difference from PhoneGap is, for example, that it uses the native components of the system, rather than creating a WebView component
NativeScript is a library that allows you to make cross-platform applications using XML, CSS, JavaScript.

Answer 2

Learn Java if you are looking to create Android Apps, and Objective C for iPhone Apps.

To learn the coding in an interesting way, you can try out codefights.com

Hope it helps...