The description is fairly self explanatory, you must have a Paladins ACCOUNT. As far as I know, this is different than simply playing the game for a year.
You'll need to go the Hi-Rez's website and link your Xbox and Hi-Rez accounts, which you can do here: https://www.hirezstudios.com/link
Follow those steps and come back a year later to earn the achievement.
As I do not have this achievement, if someone who does can add any further detail, if there is any, it's appreciated.