Python for Unity facilitates Unity's interaction with various media and entertainment industry applications and ensures that you can integrate Unity into a broader production pipeline seamlessly. It allows access from Python to the full C# API of UnityEditor, UnityEngine, as well as your own C# APIs added to your Unity projects, and running Python code from within C#.

• Python 2.7.5 (64 bits) or later. The package does not work with Python 3.
• Unity 2019.3. We recommend installing the latest version of Unity 2019 via the Unity Hub; 2019.3 is the minimum.
• Used 2019.4.17f1 LTS

• You must use Windows 10, patched to build 1803 or later.
• Install the software listed above in the default locations. When installing Python, make sure to check the option to add to the path is on.

Python for Unity requires some manual installation:

• First, follow the installation instructions in the manual
• Next, install Python for Unity itself: Edit your Unity manifest.json file (in the Packages folder of your project) so that it starts with

{
  "dependencies": {
    "com.unity.scripting.python": "2.0.1-preview.2",
    ...
  }
}

Create a script named HelloWorld.cs and attach it to the Main Camera.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class HelloWorld : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        Debug.Log("Unity: Hello World");
        print ("Python: Hello World");
    }
    // Update is called once per frame
    void Update()
    {
        
    }
}

Also you can try like this,

• Run your application.
• Go to Window -> General -> Python Console
• Type the following code in the bottom window and click on the Execute button:

import UnityEngine
print ("Python: Hello World from python console")
UnityEngine.Debug.Log("Unity: Hello World from unity console")