I am trying to sell my land. Someone wants to lease to own. How does that work?

These are two separate issues --  leasing for fair use --  and the right to purchase at a price, maybe fixed now, some time in the future.  Each has their own way to value, and they are two separate contracts which may or may not be linked with terms or conditions of default, cross default.  This requires careful drafting --  see a lawyer, as many realtors do not take the time to craft protections for you.