E3D PT100 Ampliefier board is specifically designed to allow the use of the E3D PT100 sensor.
The PT100 Amplifier board allows you to connect a PT100 sensor on a electronics solution which does not support RTD Sensing.
The board amplifies the signal coming from the PT100 sensor to a voltage which can be read on any analog input pin of most controller boards. The board is designed in such a way that selecting temperature sensor '20' in the well known Marlin firmware will allows you to get correct calibration values.
Benefit of using a PT100 is a more accurate temperature sensing and the ability for the hotend to function with temperatures up to 400°C. This high temperature is needed for more special materials like Nylon, Polycarbonate, Peek, etc. The name PT100 is derived from the material used in the sensor Platinum (PT) and the 100 ohm resistance at 0°C.