Not sure how true..... but have been told it's a hang over from the days of morse code abbreviations....
QNH = Question Nil Height
QFE = Question Field Elevation
Set QNH and your altimeter reads height above sea level - pressure setting to correct altimeter to Nil Height datum(sea level).
Set QFE and your altimeter reads zero at the aerodrome that it's accurate for - pressure setting to correct altimeter to field elevation datum.