On the following pictures, you can see a guy in green showing a panel-like device with numbers on it to the pilot of the Super-Hornet that is about to launch from the carrier USS John C. Stennis.
- What is this panel for?
- What information is the pilot given?
- Why just before takeoff and not while boarding/briefing?
Pictures taken from:at 03:46
Edit: I won't accept this question as a duplicate. It may contain the answer
Taxiing up to the catapult, a green shirt will hold up the weight board. If the weight on the board matches the weight on the weight chit, acknowledge ...
but the question isn't really about that part and quite "hidden".