To add to what Mech24 said, the red outline is the door to the RAT. It deploys if both engines quit in flight to provide hydraulic power through the center hydraulic system to the flight controls. It also can be deployed manually by a button on the upper panel in the flight deck. The red outline is to keep people underneath the plane away from below the door. The danger comes from that button in the cockpit. The RAT is spring loaded to open RIGHT NOW when the button is pushed (or if needed when both engines go out). It is a very powerful spring, and as part of our training we are told to ALWAYS stay away from underneath that door. If it opens and hits you, you're probably dead. That's why we sometimes refer to that button as the 'Ramper Snuffer'. It's in poor taste, but accurate.
One smooth landing is skill. Two in a row is luck. Three in a row and someone is lying.