When a song contains mostly notes from the F major scale, it is said to be in the key of F major. The key signature for F major contains one flat (Bb) after each clef. The next 2 songs Bojangles Boogie and On Top Of Old Smoky , are written here in the key of F.
In this song the chords played by the left hand are played arpeggio style. On the recording there are five beats to introduce this song.