I want to be able to change what variable I'm using (from another script) in the inspector.

Questions & Answers
1

I am making a prefab that can change the player stats of my player from a script. Yet i want to be able to change the stat that I’m affecting from the inspector. Is there any way to do that?

2

The method told by ShadyProductions is great but if your health variable is private and don’t wish it to make public you can use this method.

Create a method in the original Prefab script let’s say

public void ChangeVariable(float newVariable) {
 Variable = newVariable;
}

Then in the other script create a new variable (which will be seen in the inspector) let’s say its name is Health
Then use GetComponent to get reference of your first script like this

public float Health;
void Start () {
PreviousScript player = GetComponent<PreviousScript>();
player.ChangeVariable(Health);
}