This tutorial teaches how to redact Personally Identifiable Information (PII) from audio and video files using the AssemblyAI JavaScript SDK in a Node.js environment. The process involves setting up the development environment, transcribing audio or video files with PII redaction enabled, getting the PII-redacted audio file, and running the script. The final output is a redacted transcript text and an associated redacted audio file where specified PII policies are replaced with hashes or beeps.