If your vehicle rapidly closes in on the vehicle ahead because the vehicle applies the brakes suddenly while you are traveling in headway control, the warning sound activates and the brake warning is indicated in the display. Always verify the safety of the surrounding area and depress the brake pedal while keeping a safer distance from the vehicle ahead.
Additionally, always keep a safer distance from the vehicles behind you.

Mazda Radar Cruise Control (MRCC) Display Indication
Setting the SystemMazda 6 Owners Manual: Lane-Change Signals and Three-Flash Turn Signal
Lane-Change Signals
Move the lever halfway toward the direction of the lane change—until the indicator
flashes— and hold it there. It will return to the off position when released.
Three-Flash Turn Signal
After releasing the turn signal lever, the turn signal indicator flashes three
times ...
Mazda 6 Owners Manual: Using Automatic Locking Mode (Some models)
Follow these instructions when using a child-restraint system, unless you are
attaching a LATCH-equipped childrestraint system to the rear LATCH lower anchors.
Refer to “Using LATCH Lower Anchor”.
NOTE
Follow the child-restraint system manufacturer's instructions carefully. If
you are no ...