What is Tick()? And how do i use it? (Not request for script | Just education/general idea)

You're probably asking what tick() returns, right? Well, tick() is a ROBLOX built-in function that returns the number of seconds that have elapsed since the UNIX epoch (January 1st, 1970), on your computer. What do I mean with on your computer.? This will depend on how your computer's date is set. If you're looking for starting on with stuff like for example a daily reward system, you should check os.time() instead. using tick() will cause unwanted results as people can change their date to receive the reward and going on and on.

Links of the wiki:

tick()

os.time()