That's files are for work with Laravel voyager using additional options.
https://voyager.readme.io/docs/additional-field-options#section-drop-down Drop Down When specifying that an input type should be a dropdown you will need to specify the values of that dropdown. In the JSON above you can specify the default value of the dropdown if it does not have a value. Additionally, in the options object you will specify the value of the option on the left and the text to be displayed on the right.