In terms of quantum states, what is meant by energy degeneracy?

A particle of mass $m$ is confined within the box $0<x<a, 0<y<a$ and $0<z<c$. The potential vanishes inside the box and is infinite outside. Find the allowed energies by considering a stationary state wavefunction of the form

$$\chi(x, y, z)=X(x) Y(y) Z(z)$$

Write down the normalised ground state wavefunction. Assuming that $c<a<\sqrt{2} c$, give the energies of the first three excited states.