PV=NRT is basically an ideal gas formula which describes the relationship between the measurable properties of an ideal gas. In this formula, P stands for the pressure, v for the volume, n for the numbers of the moles and the r for the constant of the gas.
It is represented as the PV=NRT and not as PV= T since in the case of the ideal gas properties it is mandatory to use the Kelvin scale, as here the temperature is kept in the denominator such as (P/T or V/T). On the other hand if here we use Celsius then it won’t be an ideal solution since in that case, we have to put the 0 in the denominator.
This is the reason that why the Kelvin is used in the ideal gas formula properties since even if in the Kelvin scale we use 0 in the denominator it would still be the absolute zero, which is considered ideal. So, this is why we use Kelvin in the ideal gas equation instead of the Celsius for simplification purposes.