In this case the left-hand side is a fiduciary call, which is long a call and enough cash (or bonds) to pay the strike price if the call is exercised, while the right-hand side is a protective put, which is long a put and the asset, so the asset can be sold for the strike price if the spot is below strike at expiry. Both sides have payoff "max"("S"("T"), "K") at expiry (i.e., at least the strike price, or the value of the asset if more), which gives another way of proving or interpreting put–call parity.