To evaluate the expression \( \frac{h}{6} \) for \( h = 18 \), you substitute \( 18 \) for \( h \) in the expression:
\[ \frac{h}{6} = \frac{18}{6} \]
Now, simplify \( \frac{18}{6} \):
\[ \frac{18}{6} = 3 \]
Thus, the simplified answer is:
\[ 3 \]