Exemplar basically means a typical example, or model, of a concept or role. However the meaning can be extended to mean he best example of a concept or role. For instance, someone might say that you are an exemplar student, which can mean that you are a great example, or model, of a student.
"guitarist" is your simple subject because a simple subject<span> is a </span>subject<span> that has just one noun as the focus of the sentence. </span>