The supply voltage shows the supply of the fan
The fan rotation shows the fan speed
The fan current shown the current of the motor
The locked signal graph shows the output of the third open collector pin when a pullup resistor is used as shown in the schematic.
The power supply graph has a section named lock, as you can see by the fan rotation graph in this area the fan is stopped so you get an alarm signal at the locked pin.
In the lock release section of the supply graph you see that the rotation speed increases again and the lock signal (alarm) goes high again
What I describe is for 2C, each of the three pictures shows different behaviour , one goes low on alarm, one goes high on alarm etc