[tdlrali]

from Encoder.cpp:

/**
 * Gets the current count.
 * Returns the current count on the QuadEncoder.
 * @return Current count from the QuadEncoder.
 */
INT32 Encoder::Get(void)
{
	INT32 value = m_encoder->readOutput_Value(&status);
	wpi_assertCleanStatus(status);
	return value;
}

It returns the number of pulses received since the encoder was initialized or the count was reset.

Your other option is GetPeriod, which:
"Returns the period of the most recent Quad Encoder pulse in microseconds."