What does a flat sign do to a note?

Answer 1

A flat sign, denoted by the symbol "♭", when placed before a note, lowers its pitch by a half step. In music notation, it indicates that the note should be played or sung one semitone lower than its natural or unaltered state. The effect of a flat sign is temporary and only applies to the specific note it precedes unless explicitly indicated otherwise by a key signature or additional accidentals.