It stores your customised settings for Finder. You don't have to delete it but dragging it to the Trash (without emptying) and rebooting should have the same effect. A new default version of this file will be created in its place which will mean you'll lose your customised settings in Finder. However, if it is this file that is corrupt then your problem might be fixed too. If it doesn't work and you can't be bothered re-customising your Finder manually, you can drag the file back from the Trash and into the folder you found it in (Preferences), replace the new one, reboot and continue on like nothing has changed. 🙂