The clipboard icon copies the link to your clipboard, making it easy for you to paste and share it somewhere else.
Note: sharing your link does not give students or anyone else access to your account. They can just play the puzzle and that is it.
The Facebook icon opens up a way to share the link on Facebook directly.
The Twitter icon opens Twitter and lets you share the link directly.
The Google Classroom icon opens up a connection with your Google Classroom account and lets you share the puzzle directly there.