I’ve seen a lot of tutorials and stuff that mention that they do work with filtering enabled, but I have no idea what it is! Could someone please explain filtering enabled and what it is used for?
When filtering enabled is turned on actions made by the client will no longer freely replicate to the server. For example, this means an exploiter who places a model in the game will see it, but no one else playing would.
Here's an article that goes into more depth: https://developer.roblox.com/en-us/api-reference/property/Workspace/FilteringEnabled
This means you will have to use remote events and functions in order to communicate from the client to the server. https://developer.roblox.com/en-us/articles/Remote-Functions-and-Events
This is a really basic explanation, but hopefully, it lets you access the topic, and the articles will fill out your understanding to a competent level.