CS:GO callouts in Dust2 can be complicated much like any map in the competitive Counter-Strike: Global Offensive map pool. Dust2 might be the most iconic map in the history of the game, but the callouts are more than just about nostalgia.
If you want to compete at a high level, you must learn the callouts for each map. It can be long and tiresome, and tedious, but teammates need to be able to trust you, if you're to know where to look for enemies.
CS:GO Callouts Dust2: How to Play Dust2 Like a Pro
There are a total of 51 callouts on Dust2, and there are dozens of websites that breakdown the map for you. You can use ones like totalcsgo, which explain each callout specifically. There are iconic ones, you'll probably already know like A Long, Pit, Mid Doors, Upper Tunnels, but the specific ones across the map take your game to the next level. If you an ally covering mid doors because of T-sided push, and your teammate calls out B Boxes, that split second callout can save your life and tell you where to look for the enemy.
There is no other way around it, you'll need to practice the callouts. There is no shortcut or way around it, study the callouts, pull it up on a second monitor and try to use them as much as you can in-game.