Counter Terrorism Forces team must eliminate the thread by shooting all the enemies, which is the terrorist team. You need to move fast and don't give your enemies time to shoot you because your life will drop and you will lose the battle when you die. Shooting more enemies means more chances to survive into the army mission. Yes, that is the task: to be able to shoot before thinking about shooting them.
An arrow that is pointing at the enemy head shows the locations and movements of enemies.