JavaScript is similar in some respects to Java but it is easier to learn and a good place for beginners to start programming, or coding. In HTML5, it is a graphical programming language that is compatible with a wide range of delivery platforms including desktops, laptops and mobile devices. You can see some good examples of JavaScript apps at debden.com.
Android apps are written in two languages. One is a version of XML that is used to create user interfaces for Android mobile devices and the other is the Java code that provides the programmed action. Java is a very widely used programming language and comes in several varieties, or frameworks. There is Java for desktops, Java for web servers, and Java for Android mobile devices.
There are several alternatives to the Android framework described above. The most popular is probably Cordova which provides an alternative to the so-called native code of Android, iOS and Windows. Cordova mobile apps are written in JavaScript and a single code base can be adapted to run in all three native environments.
The easiest way to learn how to code is to use the MIT Scratch programming software. You can write Scratch programs online by registering on the MIT website. Then you can share your work with a global community of Scratchers. Or, if you prefer to code offline, you can download the Scratch 2 version and upload your work to the website if and when you feel like it.