\(\beta^-\)-decay involves the conversion of a neutron into a proton with emission of an electron (\(e^-\)) and an antineutrino (\(\overline{\nu}\)).
So, the atomic number increases by 1, mass number stays the same.
Therefore:
\[
{}^{23}_{10}\mathrm{Ne} \xrightarrow{\beta^-} {}^{23}_{11}\mathrm{Na} + e^{-} + \overline{\nu}
\]