How can I pass a global variable from ServerScript to LocalScript?

You could make a RemoteEvent about this, but you could figure out the rest yourself since it isnt that hard

lets say there is a RemoteEvent in replicatedstorage right now, named TestRemote

this is a serverscript, in serverscriptservice for example

game:GetService("Players").PlayerAdded:Connect(function(player)
	local x = 0

	x = 1 
	x = 2
	x = 3
	x = 4
	x = 5
	game:GetService("ReplicatedStorage").TestRemote:FireClient(player, x)
	x = 6
	x = 7
end)

and here is a localscript:

game:GetService("ReplicatedStorage").TestRemote.OnClientEvent:Connect(function(x) -- Warning, do not put player parameter here, it wont work because there is no player parameter in OnClientEvent, i made that mistake like 3 times lol
	print(x) -- 5
end)

Of course, you can transfer Instances too,

script:

game:GetService("Players").PlayerAdded:Connect(function(player)
	game:GetService("ReplicatedStorage").TestRemote:FireClient(player, game.Workspace.Part)
end)

localscript:

game:GetService("ReplicatedStorage").TestRemote.OnClientEvent:Connect(function(part)
	print(part.Name) -- Part 
end)

oh by the way, if your question isnt like what i answered, or you can explain a little more details on the script (you can delete some parts you dont want to show, some people do it)