Exact technical meaning really depends on the circuit.
Obviously it always has something to do with sensing current.
Typical places where I could add such a label to a net would include:
* Simple voltage as measured from one terminal from a current shunt resistor, another side being connected to GND or Vcc. This voltage is relative to the current going through that resistor
* Voltage relative to current measured using some more sophisticated circuitry, for example a hall effect current sensor, or a shunt + amplifier circuit
Very often such signal carries a voltage level that represents the measured current, for example so that 1 volt corresponds to say 10 amps or whatever.
The destination for such a signal could be a switch-mode supply controller IC so it can, using the current sense information, provide current limiting. Or it could go to an analog-to-digital converter inside a microcontroller so it can measure and log current in some circuit.