Timer Countdown Pop Up Screen Before Scene "Starts" Please Help!!

Hey everyone I was wondering if anyone could help me or point me in the right direction. I am looking to make a pop up UI that incorporates a 3 second timer countdown. Then after it is done counting, it disappears and the level is there to interact. I kind of have some experience with the UI pop up screens. I am mainly trying to figure out the countdown timer on that pop up UI. While the timer is counting down, I want the scene behind it to be “frozen or not moving” The pictures show an example of what I am looking for:

If anyone could help me out or point me in the right direction I would GREATLY appreciate it! Thank you.

@Jalah_LLC

So make it so that nothing in the scene will move until the countdown is done by using a boolean that is false until you are done with the countdown. then complete your countdown, i assume you have that part down for now? if not i can assist with that as well. but surrounding the game code with a while(countedDown) should help you get the job done.

let me know if it helps !

@Redwolve I do appreciate the input!

So make it so that nothing in the scene will move until the countdown is done by using a boolean that is false until you are done with the countdown. then complete your countdown, i assume you have that part down for now?

I actually do not have that part down lol. If you could help me with the code for that, or point me in the right direction I would GREATLY Appreciate it! Thanks.