Thunar is a file manager, and with its plugin in Kupfer you can initiate a number of actions: empty trash, select file in thunar, show file properties, copy file to (...), move file to (...) and make symlink to file in (...).
Power User Tips
In Thunar itself configure a custom action for selecting files in Kupfer: Create a new custom action called Send to Kupfer with the command kupfer %F and enable it for all files.
If you can, temporarily enable editable menu accelerators to assign a shortcut key to the new custom action. If you now select files in Thunar and press the shortcut key, Kupfer will be summoned with the files selected.