Meaning of N parameter in Chan Model LTspice
N is part of the Chan core parameters (along with Br, Bs, Hc, A, Lm, Lg) and it means the number of turns. In this configuration (the one you're showing) it's part of the magnetizing inductance. This is used as a one turn inductor with all the parameters of the Chan core, so that the combination of VCVSs/CCCSs that make up the windings can use the full number of turns.
In case my words are fuzzy, think of it like this: you can have a one turn magnetizing inductance and then model the windings, each with its own number of turns, or you can have a magnetizing inductance with a certain number of turns and then model the windings with percentages of those number of turns.
E.g.: for Np=100, Ns=25 you can have:

Nmag=1, Np=100, Ns=25
Nmag=100, Np=1, Ns=0.25

You can also use Nmag=10, Np=10, Ns=2.5, or any other numbers that satisfy the ratio, but it would just look confusing. For the same reason, Nmag=1 is used, to let both Np and Ns be meaningful to what they represent.