  We present the results of the investigation of the nova V1674 Her (2021),
recognised as the swiftest classical nova, with $t_2 \sim 0.90$ days. The
distance to the nova is estimated to be 4.97 kpc. The mass and radius of the WD
are calculated to be $\sim~1.36~M_\odot$ and $\sim 0.15~R_\oplus$,
respectively. Over the course of one month following the outburst, V1674 Her
traversed distinct phases -- pre-maxima, early decline, nebular, and coronal --
displaying a remarkably swift transformation. The nebular lines emerged on day
10.00, making it the classical nova with the earliest observed commencement to
date. We modelled the observed optical spectrum using the photoionization code
\textsc{cloudy}. From the best-fitting model we deduced different physical and
chemical parameters associated withe the system. The temperature and luminosity
of the central ionizing sources are found in the range of $1.99 - 2.34~\times
10^5$ K and $1.26 - 3.16~ \times 10^{38}$ \ergs, respectively. Elements such as
He, O, N, and Ne are found to be overabundant compared to solar abundance in
both the nebular and coronal phases. According to the model, Fe II abundance
diminishes while Ne abundance increases, potentially elucidating the rare
hybrid transition between Fe and He/N nova classes. The ejected mass across all
epochs spanned from $3.42 - 7.04~ \times 10^{-5}~M_\odot$. Morpho-kinematic
modelling utilising \textsc{shape} revealed that the nova V1674 Her possesses a
bipolar structure with an equatorial ring at the centre and an inclination
angle of i = 67$\pm$ 1.5$^{\circ}$.
