Detect motion from people or animals to trigger an event. Could be an alarm, a notification (email or text), trigger a video or sound playing. There's lots of possibilities.
Connect VCC to 5V, GND to GND and the middle pin is the output port, which is 3V3 safe. Connect that to an input port on your Raspberry Pi, Arduino, Wemos etc. Output port goes HIGH on triggering.
Two potentiometers are for adjusting the sensitivity (Sx) and duration (Tx) of the trigger.