First and foremost: this achievement is noted to be very buggy. As with every achievement that glitches on the Xbox one ; deleting your account, redownloading it, hard-resetting or just giving microsoft time to pop the achievement eventually are all options worthy of consideration.
Nonetheless...below is a description of what SHOULD happen.
After playing about 10 games in the ranked multiplayer playlist the game will give you a temporary assesment based on your performance during these first few games and hand you a skill rank. This skill rank is an indicator of your skill level ( You can promote and demote) contrary to your level which is a mere indicator for how long you have played.
Some users have noted that they have to search for another match after receiving their skill rank before the achievement would unlock.
There are couple of differences when playing ranked ( compared to casual):
Ranked matches have voting on spawn/objective location
Ranked matches do NOT have Death Replays
Ranked matches will utilize a minimal HUD setting
No scoring indicators
No grenade indicators
No threat indicators
No reload indicators
No teammate outline
No kill confirmation marker