Rhindon - your definition of dt as "the amount of time passed BETWEEN ticks/FPS DURING a SINGLE SECOND" is not exactly right. It's not averaged over a second or anything like that. dt is literally only the time in seconds since the last tick - that is the full definition. It normally is about 16ms or 0.016, corresponding to a screen refresh rate of 60 Hz (since 1 / 60 = 0.016), but can change depending on the framerate.
However dt has the property that over one second, the sum of every frame's dt also adds up to a second. (Hopefully that's faily obvious!) In fact over any period of time T, dt will sum to equal T.
That means that if every tick you add dt to a number, it increases by 1 a second. Therefore, if you add n * dt to a number, it increases by n every second. This isn't to do with the actual definition of what dt is, it's just what mathematically follows from how dt works.
The reason I chose 60 * dt in the example and not a different number is if you have done the following event -
Every tick: set sprite X to Self.X + 1
then this is framerate dependent, and moves at different speeds depending on the framerate. However, most computers are fast enough to render at the screen refresh rate, which is usually 60 Hz. So most of the time it will move at 60 pixels per second. If you want an object to move at 60 pixels per second in a framerate independent way, you would use Self.X + 60 * dt. As we showed before this will move the object 60 pixels a second, regardless of the framerate. So you can make changes like this and the object will probably appear to move at the same speed, but now it's framerate independent.
Hopefully that helps clear it up!