The phrase “don’t dally” means to avoid wasting time or being slow in taking action. It is often used as an encouragement to be prompt, efficient, or to hurry up. The term “dally” itself means to spend time aimlessly or to linger without purpose. Therefore, when someone says “don’t dally,” they are urging someone to get moving or to focus on the task at hand rather than procrastinating or dawdling.