This board is specifically designed for the TSC101 integrated circuit. The TSC101 measures a very small voltage drop across a high-side shunt resistor, and using an internally fixed gain, amplifies the difference into a ground-referenced output voltage.

Independent supply and input common-mode voltages
Wide common-mode operating range: +2.8 to +30V
Wide common-mode surviving range: -0.3 to +60V (load-dump)
Wide supply voltage range: +4 to +24V
Low current consumption: Icc max = 300μA
Internally fixed gain: 20V/V (TSC101A), 50V/V (TSC101B), 100V/V (TSC101C)
Buffered output

Current Sensing Amplifiers have a voltage output that is proportional to the volt drop across a very low value resistor, usually in a high-current power rail. Hence they measure the current flowing in that power rail.