_G Can be used for Global Variables/Arrays. You can learn more about it at Lua Globals (It is at the bottom of the Page)
For example, You can declare the Variable at a certain script:
-- First script
_G.MyName = "Crunch"
And use it on another one! It’s recommended to yield (wait) for a small time as it may take a very small amount of time to be accessed.
-- Second Script
task.wait()
print(_G.MyName)
Using Global Variables (_G or shared) for holding/storing Data (or even manage it) is not the best idea. I recommend you taking a look at ModuleScripts to understand more about them, And if you’re looking towards saving data, I recommend you using ProfileService.