Left half yellow, right half blue, Kilo stands for "K" in the signal flag alphabet. It's the final contender in our 3 way sweepstakes for the new IKEA flag. Since IKEA has a K I guess that's how you're going to have to remember this one. Good luck with Delta and Golf though.
Kilo means that the flying vessel wants to communicate with another ship, which is similar to Foxtrot. But in this case the vessel isn't disabled, it just wants to talk. They can get a little more specific about the means of communication if they want by adding numbers onto the end.
Check out the rest of our Signal Flag explanations!