What does "Objective Available" indicate?

Hello everyone,
I’m new to the game and I see those yellow marks in the hangar that say “Objective Avaiable” but I cannot understand what exactly that means or where to find more information about it, could someone guide me ?

Pages of history, if you go to your player card, acheivements, then History pages, you can play the specific vehicles and get a profile picture

Thanks a lot for the explanation, I checked it out! :)

The profile picture i am using now was one of the pages of history profile pics, some of them are worth going for, for example the most recent one is Desmond Doss, but when it is just some russian guy who rammed his plane in to a convoy that noone knows i dont blame anyone for taking a month off