Confused about buyout options for lease

I have a Kia K5 2023 GT lease that ends next month. I have two payments left on it. Residual value is $18K with no additional purchase option fee per my contract.

I’m confused how the buyout options work as this is my first lease. Do I have to pay an additional $18K to own the car or what do I have to pay in the end to own it? Sorry if that’s a dumb question as I’m new to all this.

Would it be a better option to have another dealership buyout my lease and use that equity as the down payment for another lease?