We are given the energy of the nth orbit of the hydrogen atom by the equation:
\[
E_n = - \frac{13.6}{n^2} \, \text{eV}
\]
For the second orbit (\( n = 2 \)):
\[
E_2 = - \frac{13.6}{2^2} = - \frac{13.6}{4} = - 3.4 \, \text{eV}
\]
Thus, the energy of the second orbit is \( - 3.4 \, \text{eV} \).