The Heartbeat event fires every frame in the
RunService. The step argument indicates how much time has passed between frames - usually around 1/60th of a second.
Please note that this will vary depending on the performance of the machine. If the game is only running at 40 FPS, that means that Heartbeat will fire 40 times per second, and the step argument will be roughly 1/40th of a second.
Indicates how much time has passed between frames
Printing Heartbeat Frequency
The following example will print the time between each Heartbeat loop 5 times - while the value of count is less than the value of loopCount.