For example 2 scripts could both use 1 variable.
You can use a IntValue that is parented in 'Replicated Storage'(If you want a client & server script to acces to that value). You can also use a attributes that can be inside of a script or any instance you want. (If you change a value in a local script, the server will not detect that the variable changed.)
you can use _G to store variables between multiple normal scripts
example:
_G.variable = 10
another normal script will be able to access it