these are the keys that operate the fute. There are two more on the back, operated by the thumb. If you press no keys, it plays G. f you use the left column of keys it plays F, E and D.
The small keys are (from top to bottom): top trill key, auxilliarry bB key, lower trill key, #G key.
The keys for bB and #C are one the back of the flute and are operated by the thumb.