Android uses Java for programming and XML for displaying stuff on the screen. Java is a high-level OOP language, and it's fairly easy to learn. I recommend picking up an Android app development book, and a java programming book. You should familiarize yourself with basic Java programming and Object Oriented Programming before continuing with actual Android app development. Jumping too far in without knowing the basics will cause confusion, and you'll probably give up if you rush learning it.
Getting Started with Android Development Using Eclipse
This site should help you get set up.
What your going to need is:
Eclipse IDE (Integrated Development Environment) which is like Notepad except its so much more. It manages your projects, imports libraries and files, and assists you in coding your program. This is where you do your typing/coding.
Android SDK (Software Development Kit) which is the Android libraries and tools, which is code already programmed for you.
Java JRE (Java Runtime Environment) which allows you to run Java applications. This may already be installed on your computer.
Java SDK which is similar to Android SDK, but only for Java. It allows you to create Java applications.
ADT plugin for Eclipse (Android Development Tools) this allows eclipse to use Android tools and Virtual Device.
The Android Emulator (Android Virtual Device) comes with the Android SDK and is ran through Eclipse.
There are plenty of sites and books that walk you through the setup process.