The Express sample application is a call center experience where stranded aliens can call an agent for instructions on how to get off Earth safely. The application allows agents to screen calls, connect with callers, and record voicemails. The code uses Twilio's VoiceResponse API to create an interactive voice response (IVR) system. The IVR includes features such as routing the call to an extension based on the caller's input, dialing the agent's phone number, and displaying recordings of voicemails. The application also handles scenarios where agents are unavailable or have left a message after the beep.