The Android emulator allows developers to test Android applications without using physical devices. It simulates key aspects of an Android device including hardware, software, and various form factors. The emulator runs on the computer and displays an emulated Android device that developers can interact with. It supports running multiple emulated Android devices at once with varying configurations defined through Android Virtual Devices (AVDs). The emulator and AVDs allow easy prototyping and testing of Android applications across different device profiles before releasing to physical hardware.