This means in detail:

Detecting = identifying a safety-relevant request.

e.g. if an EMERGENCY STOP button is pressed or a hazardous area, protected by sensors, light grids or laser scanners, is entered.

Evaluating = identifying a safety-relevant request and safely initiating the response.

e.g. shutting down the enable circuits.

Shutting down = shutting down the potential danger.

e.g. a power supply using the downstream contactor.

Functionality at a glance
Time is money. In order for you to quickly understand the specific functionality of the individual device types, This is how it works: At a glance you can see the inputs in the sensor interface, the outputs
and enable circuits in the actuator interface and the special safety logic.
In order to keep everything simple, the schematics only show the inputs and outputs that are required to explain the safety function.
The power supply inputs and the sensors as well as actuators that
can be connected to the interface have not be taken into account as
they are not relevant for explaining the function.