  We present spectroscopic observations of Nova Cas 2020(V1391 Cas) obtained
using the Russian Turkish Telescope during different stages of its 2020
outburst. We followed the spectral evolution of the nova until it entered the
nebular phase. The expansion velocity of the ejecta reached $\sim$780
$\mathrm{km\,s^{-1}}$. The fluxes of the neutral [O I] lines at wavelengths
6300, 6364, and 5577 $\r{A}$ were used to calculate the electron temperature
and the mass of neutral oxygen in the ejecta. We found average values $T_e =
4890\,K$ ,$M_{OI} = 2.54 \times 10^{-5}\, M_{\odot}$ which are consistent with
the values calculated for other novae. We modeled the nova's ejected envelope
515 days after its discovery and found that the log elemental abundances by
number relative to Hydrogen of the envelope are He = -0.7, C = -5.5, O = -2.5,
N = -2.0 and Ne = -4.0.
