How to save a number value on game server and NOT a PLAYER?

im trying to save a value on the game server so when anyone joins they will have the same value. the value will be updated when a player clicks a button. im trying to make the VALUE get saved so when the server shuts down, it will still be back.

I really tried my best but couldnt fighte out, would love to get some help.

I think you're referring to datastores,

https://developer.roblox.com/en-us/articles/Data-store