  We report the temperature dependent dielectric properties and impedance
spectroscopy investigation of Na$_3$Zr$_2$Si$_2$PO$_{12}$ in the frequency
range of 20 Hz--2 MHz. The Rietveld refinement of x-ray diffraction pattern
confirms the monoclinic phase with C2/c space group. The {\it d.c.} resistivity
behavior shows its strong insulating nature at low temperatures, and follows
Arrhenius law of thermal conduction with an activation energy of 0.68 eV. The
decrease in electric permittivity ($\epsilon_r$) with frequency is explained
based on the space polarization mechanism and its increment with temperature by
thermal activation of charge carriers. The dielectric loss (D=tan$\delta$) peak
follows the Arrhenius law of thermal activation with an energy of 0.25 eV. We
observe an enhancement in {\it a.c.} conductivity with frequency and
temperature due to the decrease in the activation energy, which results in
enhancing the conduction between defect states. Further, we observe an abrupt
increase in the {\it a.c.} conductivity at high frequencies, which is explained
using the universal Jonschers power law. The analysis of {\it a.c.}
conductivity shows two types of conduction mechanisms namely correlated barrier
hopping and non-overlapping small polaron tunnelling in the measured
temperature range. The imaginary part of the electric modulus confirms the
non-Debye type relaxation in the sample. The shifting of the relaxation peak
towards higher frequency side with an increase in temperature ensures its
thermally activated nature. The scaling behavior of the electric modulus shows
similar type of relaxation over the measured temperature range. The combined
analysis of electric modulus and impedance with frequency shows the short-range
mobility of charge carriers.
