How Do I Save/Load Numbers?

i'm trying to make stats for our game but something is really bugging me i cant seem to understand on how to Save/Load Numbers or Values

the stats are just numbervalues saved in the plr but how can i save that number so the player could leave and join and still have them (saving and loading)

For this, you should use Data Stores (You may wish to see the 'See Also' section of that page). While you could use the old data persistence, I (and few others) would recommend it.