To find the value of \( f(4) \) for the function \( f(x) = x^2 - 5 \), you can substitute \( x \) with \( 4 \):
\[ f(4) = 4^2 - 5 \]
Calculating \( 4^2 \):
\[ 4^2 = 16 \]
Now subtract \( 5 \):
\[ f(4) = 16 - 5 = 11 \]
Thus, the value of \( f(4) \) is \( 11 \).