The right of first purchase (also known as option right) means that you can choose to buy a property at a negotiated price within a certain period of time. At the same time, the object cannot be sold to others. The seller must give you the right to buy first. Municipalities also often invoke the first purchase right for certain plots and plots. This way they can carry out their plans and fight land speculation.
If, as a tenant, you want to buy a rented property after the rental period has expired, you can include a clause in the rental agreement that gives you the right to make the first purchase (at a reasonable market price!).