Simplify the following text for a Grade 8 native English-speaking person.
Original: More specifically , in music notation , flat means , `` lower in pitch by a semitone ( half step ) , '' and has an associated symbol , which is a stylised lowercase `` b '' that may be found in key signatures or as an accidental , as may sharps .
Simplified: In music notation , flat means `` lower in pitch by a semitone ( half step ) , '' and has the symbol .