Answer is: The electrons moved from the second energy level to the fourth.
Atomic number (Z) of sodium is 11, it means that it has 11 protons and 11 electrons, so atom of sodium is neutral.
Electron configuration of sodium atom in a ground state:
₁₁Na 1s² 2s² 2p⁶ 3s¹ or 2-8-1-0.
In a ground state of sodium atom, fourth energy level is empty.
In a excited state electron from second energy level (2s² 2p⁶) moves to fourth energy level.