On models with remote central lockiing, "Safe Lock" is a reminder that the doors will be deadlocked with a single press of the lock button on the key remote - that's why the locks clunk twice when you lock or unlock. If you don't want the deadlocks set, you have to press the lock button twice within 2 seconds. On most cars (certainly the ones I've had) it's the other way round, with two presses needed to set the deadlocks. See "Safe Securing System", handbook page 25.
The two symbols in the LCD display indicate whether or not the rear seat belts are fastened. Page 22 in the handbook.