Basically, Delta Time is the amount of time from each frame. So no matter what fps the project is at, the Sprite with it will always move at the same speed because it moves (10 * Delta Time steps), while the sprite without it just moves 10 steps. You can go to turbowarp and change the fps, and the sprite with it will always move the same amount.
Although Delta Time is used everywhere I learned about it in an Unreal Engine tutorial.
