This is to unlock the Bombshells outfits for Joule ,Rama and Red Card
complete each characters personal operation.
Joule - Technologia
Rama - Raging Arrow
Red Card - Big Game
when all of the above have been completed you will see a new operation called Bombshells. Complete this and you will unlock the outfit for each character.
Once you have the outfits ,equip them on each character in the loadout screen before you deploy to unlock the achievement.