There's no "error", that's just the toString() representation of your Persone objects. I don't know JavaFX, but Swing uses toString() by default to display values; you can use renderers (ListCellRenderer, TableCellRenderer, TreeCellRenderer) to modify the way objects are displayed. I'm sure JavaFX has some similar mechanism. A quick search leads me to believe that Cell / ListCell is that mechanism. From the API of ListView:
Customizing ListView Visuals
The visuals of the ListView can be entirely customized by replacing the default cell factory. A cell factory is used to generate ListCell instances, which are used to represent an item in the ListView. See the Cell class documentation for a more complete description of how to write custom Cells.