In the beginning of play, you will create a character soon after selecting a class. You can then change the appearance and outfit of your chosen hero in the character creation screen.
The three empty slots in the “Select Character” screen suggests that a player can create three different character classes.
To unlock additional character slots in Black Desert Mobile, you will need character slot expansion coupons. You can obtain these coupons using black pearls.
To purchase a coupon, tap “Hot” (Pearl Shop) > Misc. > Etc. You will need 120 black pearls to obtain an expansion coupon and 120 normal pearls to buy another one.
You can obtain black pearls for free by completing achievements, located under Menu > Tasks.
If you don’t want to purchase an expansion slot, follow this trick:
Select the appropriate region and login to the game using your Google account. Create a character or characters. You can create three characters in your current account as there will be three empty slots unlocked in the beginning.
Close the app and open it again. The game will ask you to select an account to login. Instead of selecting Google account, you can tap “sign in as Guest”. If this option is not available, tap on “Logout” on the upper right side of the screen and then sign in as guest.
As a guest, you will again have to start from scratch. But you will have three empty slots in the character selection screen of your new guest account.
For example, you can create three Black Desert Mobile classes – Warrior, Ranger and the Witch in your Google account and the other two – Giant and Valkyrie in the guest account. Here’s what I did:
Google Account Characters 
Guest Account Characters
While playing, you can easily switch between your characters in your Google account and Guest account by logging into the appropriate account.
If you are signed in to your Google account, tap the menu button on the top-right corner of the screen and then tap “characters”. Next, tap on “Go to Lobby” and touch the arrow button beside “select character”. You can now sign in to your guest account and play with other characters you created on this account.
Please note that your Guest account will be permanently deleted if you delete your app and reinstall it. You can’t access your guest account on a new device.
We recommend following the above steps in the beginning, so that each character in your Google and Guest account can be leveled up at the same time when you play all five or your chosen classes at the same time.