A more thorough explanation:

ad factum praestandum

Ad factum praestandum is a legal term that means "for the performance of a particular act." It refers to an obligation to do something other than paying money. This obligation must be strictly fulfilled, such as handing over a vase that was sold.

One example of ad factum praestandum is when someone sells a car to another person. The seller has an obligation to transfer the ownership of the car to the buyer. This obligation must be strictly fulfilled, and the seller cannot simply give the buyer the money instead of the car.

Another example is when a landlord rents out an apartment to a tenant. The landlord has an obligation to provide a safe and habitable living space for the tenant. This obligation must be strictly fulfilled, and the landlord cannot simply give the tenant money instead of fixing a broken window or repairing a leaky faucet.

These examples illustrate how ad factum praestandum refers to an obligation to perform a specific act, rather than just paying money. The obligant must fulfill their obligation exactly as it was agreed upon, and cannot substitute money or anything else in its place.