Here's what each of these specifications means:

Model (SN04-N2): This is the specific model or part number of the proximity sensor switch module.

Type (NPN): NPN stands for "Negative-Positive-Negative." In the context of proximity sensors, it refers to the type of output the sensor provides. NPN sensors switch the output to the negative supply voltage when they detect an object within their detection range.

Operating Voltage (DC 6-36V): This sensor can operate within a voltage range of 6 to 36 volts DC. It means you can power it using a direct current (DC) voltage source within this specified range.

Detection Distance (5mm): This sensor is designed to detect objects at a maximum distance of 5 millimeters from its sensing face. If an object comes within this range, the sensor will trigger its output.

Connection (Normally Connect): This indicates the default state of the sensor's output. In the "Normally Connect" state, the sensor's output is connected (closed) when there is no object detected within its sensing range. When an object is detected, the output disconnects (opens).