Create custom inspector box

I am working on a simple game that deploys units from spawners after so many seconds.

I would like to put these three variable into a box similar to the box below, where I can hit the add button and type in two or three number and maybe have a drop down box to select, which carries the info to the script to deploy the units. I am doing my scripting in C#


Is this possible? What would this be called so I could look it up, or how would I do it? Its not something I must have for the game but it would save a lot of time.

public gameobject mySpawnablePrefab;

public void spawnMyPrefab()  

any variable you want you can define it at the top as

    public int myint;  
    public float  playerHelth;  

and it will show up in inspector when you add that script to a gameobject