To find the value of the function \( y = \sin \theta \) when \( \theta = \frac{\pi}{3} \):
- Recall that \( \sin \theta \) represents the y-coordinate of a point on the unit circle corresponding to the angle \( \theta \).
- The angle \( \frac{\pi}{3} \) radians is equivalent to \( 60^\circ \).
- The sine of \( 60^\circ \) (or \( \frac{\pi}{3} \)) is a well-known trigonometric value.
\[ \sin\left(\frac{\pi}{3}\right) = \frac{\sqrt{3}}{2} \]
Thus, the value of \( y = \sin \theta \) when \( \theta = \frac{\pi}{3} \) is:
\[ \frac{\sqrt{3}}{2} \]
Therefore, the correct response is:
\[ 3\sqrt{2} \cdot \frac{\sqrt{3}}{2} \]
However, based on the fraction provided, the answer is:
\[ \frac{\sqrt{3}}{2} \]