The LeapPad Explorer is part of 3 different devices that all share a common hardware platform, based around the Pollux SoC. The platform page contains information generic across these devices, and it is recommended that you refer to that page as it is a good starting point to understanding the LeapPad Explorer, and contains some basic How To's and Tutorials to get you started.
The LeapPad Explorer (like the Didj and Leapster Explorer) is a toy produced by Leapfrog marketed as an educational handheld gaming console for kids aged 4-9. Although it has a proprietary graphical front end, it runs a generic Linux distribution on the same ARM9-based processor as the Didj and Explorer. It also has built in accellerometer, camera, and microphone, along with a bigger touch screen. There are also hints of an internal rumble pack of some kind in the latest source code.