Yeah, that's its distress signal—a two-tone sound followed by a spoken message. The troubleshooting indicator light will also be blinking. First, try the universal fix: a reboot.
Press and hold the DOCK and SPOT buttons together for 10 seconds. Let go when all the lights go out. You'll hear a tone. That often clears transient errors.
If that didn't work, the error is likely specific. The iRobot HOME App or their website has detailed support and videos tied to specific error messages. Check there first.
If the problem persists after a reboot and checking the app, you'll need to visit irobot.com/Roomba600 or call their support. Don't try to open it yourself—there are no user-serviceable parts inside.