How do i make a script that edits the values of another script?

Please explain in depth.

If both are Scripts or both are LocalScripts, you can use ModuleScripts (otherwise, look up RemoteEvents and RemoteFunctions - there's even guides on ScriptingHelpers at the top of the page).

ex:

--ModuleScript named "Module" in ReplicatedStorage
local module = {}
module.var = 0
return module

--Script 1
local module = require(game.ReplicatedStorage.Module)
module.var = 10
wait(1)
print(module.var) -- 20 because of what Script 2 does

--Script 2
local module = require(game.ReplicatedStorage.Module)
wait(0.5)
print(module.var) -- 10
module.Var = 20

Of note, you cannot change the value of a local variable in another script. That is, if Script #1 has local var = 5, you cannot change that value directly from a different script.