How do I make my script repeat? ( I have read some of the other threads but they dont help)

The reason in which your script isn't working is that the if statement is only activated once as the lighton variable is true. When the script finishes, you change the variable lighton back to true, meaning the if statement isn't going to be used and ignore all of the brick colours changing. The way you can do this is by removing the if statement, as it technically has no reason to be there.

while true do
	--if lighton == false then (This if statement also isn't needed)
	 
	wait(.3)
	one.BrickColor = BrickColor.new("Really red")
	wait(.3)
	one.BrickColor = BrickColor.new("Institutional white")
	wait(.3)
	two.BrickColor = BrickColor.new("Really red")
	wait(.3)
	two.BrickColor = BrickColor.new("Institutional white")
	wait(.3)
	three.BrickColor = BrickColor.new("Really red")
	wait(1)
	three.BrickColor = BrickColor.new("Institutional white")
	--lighton = true (This isn't needed)
end

Apologies for the incorrect formatting, I am on mobile as I can't do 'Tab', if this doesn't work simply just comment and if my answer is correct please click 'Accept answer'.