h11 is the impedance of the resistor.
I1 is the current through the resistor
The voltage across the resistor is therefore h11 multiplied by I1 which is written here as h11 I1
V1 is equal to the voltage across the resistor added to the voltage across V2, so that is written as V1 = h11 I1 + V2
Notes:-
I don't understand equations (i) or (ii) or how they apply here. The h12 V2 term in equation (i) looks wrong to me.
Your link to the tutorial goes to the wrong place.
If currents are ac, and the impedances are not simple resistors, the same equation apply and Kirchhoff's laws still apply, but the currents, voltages and impedances have to be expressed as complex numbers.