idealista/maps shows publicly accessible data of all the properties that are registered in the land registry in Spain, whether they are advertised on idealista or not. The information shown corresponds to the public cadastral information of the properties, as well as to the public and non-personal data that may have appeared in property listings on idealista if the property has been advertised at some point.
The fact that a property is visible on idealista/maps does not imply that it has been or is available for sale or rent. In the event that a property is available for sale or rent, this will be expressly informed.