Other ways of playing Bb can be found in the in the Index of Fingerings section. When a flat note is written on the staff, the flat sign is placed before the note.
The flat sign affects all B notes within the bar in which it appears. For example, in bars 1 and 4 the b sign appears before the first B in each bar. The flat also applies to all other B notes within that particular bar. The effect of a flat sign is cancelled by a bar line, meaning that a new flat sign is needed to indicate a new Bb note in the following bar.