The letter is in english and korean, with the following text:

Dear Customer,

First of all i would like to thank you for choosing Air France.

it is always our great pleasure to welcome you on board our flight. Today i am very pleased to offer you an upgrade to First class (La Premiere) in order to extend our gratitude to your loyalty to Air France.

Then its a long text with what La Premiere is

I hope that today's experience will let you choose our First class service on your next travel.

Bon Voyage

Gilles Roche
General Manager
Air France Korea

Thats it