The instruction 'D.S.' signals the performer to:

The instruction 'D.S.' stands for "Dal Segno," which is an Italian term meaning "from the sign." When a musician sees 'D.S.' in the sheet music, it instructs them to return to a specific sign marked earlier in the piece, usually a symbol that looks like an S with a line through it. This indicates a repeat of the section from that point onward.

Understanding this notation is crucial for interpreting pieces correctly and ensuring that the structure of the music is followed as intended by the composer. There are various repeat signs and instructions in music, and 'D.S.' is one of the more common ones used in compositions. It serves as a clear directive for the performer, helping to guide them through the piece while noticeable changes in dynamics or articulation may occur as the music develops.