To shift the function \( f(x) = (x + 1)^3 \) to the left by 3 units, we need to replace \( x \) with \( x + 3 \). This leads to the following transformation:
\[ f(x) = ((x + 3) + 1)^3 \]
Simplifying this gives:
\[ f(x) = (x + 4)^3 \]
So, the equation describing the shifted function is:
\[ f(x) = (x + 4)^3 + 0 \]
Thus, the final result is:
\[ f(x) = (x + 4)^3 + 0 \]
To fill in the blanks:
\[ f(x) = (x + 4)^3 + 0 \]
So, the answer is \( f(x) = (x + 4)^3 + 0 \).