ATTENTION PLEASE: if you are not reading this article in English, I highly recommend that you turn off the automatic translation on your browser.
“To see somebody off” means “to say goodbye to somebody who is going to start a journey”, for example at the airport or at the train station.
Example: “We went to the airport to see Jane off.”
Meaning that we went to the airport in order to say goodbye to Jane and watch her starting her journey.
Thanks for visiting YouGrammar.com – By Marco Cossu