Hi Marina,
if you have the Google Maps autocompleter enabled, that placeholder is added by Google and can’t be modified. (maybe with jquery, but I’m not 100% sure)
Otherwise you should find that in :
plugins/geodirectory/geodirectory-languages/geodirectory-en_US.po
You should open that file with Poedit, translate the placeholder, save the file as :
geodirectory-it_IT.po
That will create the file geodirectory-it_IT.mo (in the same folder where you saved the po file), which needs to be uploaded in wp-content/languages/geodirectory/geodirectory-it_IT.mo.
Only the mo file as the po files are only to be used to create the translation and the mo file.
More info here: http://docs.wpgeodirectory.com/translate-core/
Let me know how it goes,
Thanks