What are the keys corresponding to the shortcut?

Apple's Help menu in the finder has an article titled What are those symbols shown in menus? - the related articles at the bottom are great reading. Your specific answer is:

shift+fn+delete

The up arrow ⇧ is the shift key and the symbol ⌦ is the Forward delete symbol. Typed fn+delete.

Refer to Mac keyboard shortcuts for further information on the symbols.