First, you need to create a custom section/tab/panel. Please go to Settings -> Single Property Page -> Property Settings Tabs and provide the section name you want to create and save the settings.
Now you need to add fields into this newly created section. Please go to the Property Fields menu and drag a field into the fields from the left fields panel and fill the field related info. Make sure you choose your newly created section from the Admin Settings Tab.
Now whenever you will add/edit a listing, that section will also appear with the new field as below
and in the frontend, it will display like this