For PDF files if you want the generic PDF icon and not a copy of the file itself, you'll first need to do a File->Get Info, select the icon in the Get Info window, press Command-C on your keyboard ...

Copy: The icon on the far left is “Copy.” Cut: Second to far left is “Cut.” Paste: In the middle is “Paste.” Select all: The dotted box with four filled in boxes inside second to right ...