Like a magnetic speaker, it needs voltage with different frequency so that it can make sound accordingly. The pitch becomes louder when the frequency gets higher.
Description of Pins
General Pin Out
Sensor / Trinket's Pin Out
General Pin Out is the standard pin out of a Sensor / Trinket connector.
Sensor / Trinket's Pin Out is this specific Sensor / Trinket's wiring in relation to the General Pin Out.
SIGNAL-A / SIGNAL-B are signals that could be digital input, digital output, analog input or analog output. Or special signals such as serial communication (SoftwareSerial, IIC (I2C), etc) or other special signals.
Not Connected refers to the Pin not being used for this particular Sensor / Trinket.