Kickoff is like a big rally where the game is introduced (for most of us by real time broadcast). They will have a few speakers, but the majority of the kickoff is based around FIRST showing us the real field and how to play the game. They often will mention new kit of parts items and any other specifics that might be important to the year. And they usually have some sort of question answer period.
The other fun part is that this may be the first time you get to meet some of the other teams in your area.
Some of the events will have seminars that are often very useful to planning and working through the season *I would recommend having at least one member at each seminar if your location is hosting them.
At the end of kickoff they will give us a password to unlock the documentation, we can go pick up our kit of parts and start brainstorming!!
Next to the competition, this is probably the most exciting and anticipated event in FIRST
So have fun!