The Ranked Game mode will be unlocked once you reach player level 8 and you've collected 6 or more heroes (you must own them, not the ones on free rotation). The ranking system is divided by divisions and later on by points, so depending on how well you do in your games, you will be able to rank up (or down, in more unfortunate situations) the ladder.
If you are new to the game, ranking might be a little bit confusing, especially more so if you are new to the genre. Ultimately, my journey came to an end somewhere around the mid-Epic rank, so I can't really complain. And just like every other player in love with the genre, I've played one too many ranked games, trying to reach the Mythical Glory rank. Like a true MOBA player, I've played my fair share of Mobile Legends games. Have you ever wondered what all the ranks are in Mobile Legends: Bang Bang and how the ranking system works?