Final answer:
A flag in music notation represents the duration of a note, and it is used to indicate shorter note values.
Step-by-step explanation:
In music notation, a flag is a visual symbol that represents the duration of a note. It is used to indicate shorter note values in relation to the basic note durations. Flags appear on the stems of notes, and their number determines the precise duration of the note. For example, a single flag on a note stem represents a single eighth note.