Android Sandboxing is a security feature that isolates android application data and code execution from other android applications. To perform sandboxing, the user assigns a unique ID (UID) to each application and runs it by it's own processes.
Android uses this UID to setup a kernel level application sandbox. The security benefit of using this application sandboxing is that if one application is trying to do something malicious of another application, the operating system will prevent it because the first application didnt get appropriate user privileges.
Since application sandbox is in the kernel so all the layers above the kernel like libraries, application framework, etc run within the android application sandboxing.
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