In a tutorial about h parameters of a two port network, I find the below snippet in the image unable to grasp. According to KVL, the total voltage in a loop is the algebraic sum of the individual voltages. But why in this tutorial ( equation 1 in below image ) it's given so. It should be something like V1 = h11 I1 + V2 according to KVL. What is this h12 V2 mean?
The whole tutorial is here. https://www.electrical4u.com/hybrid-parameters-or-h-parameters/