K_linear part description in Pspice
The k_linear is a parameter to describe the coupling between inductors with 1 being a perfect coupling/transformer. Its sub-parameters L1, L2 etc. describes which inductors is coupled.
As an example, if you have 2 inductors forming an transformer, and their reference designator was L6 and L7, you would specify L1=L6 and L2=L7, to let the simulator know that these is physically coupled(Like on a transformer core):