// Prints name of the font that customStyles[0] is using

function OnGUI() {
    if(GUI.skin.customStyles.Length > 0)
        Debug.Log("Font name: " + GUI.skin.customStyles[0].font.name);
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void OnGUI() {
        if (GUI.skin.customStyles.Length > 0)
            Debug.Log("Font name: " + GUI.skin.customStyles[0].font.name);
        
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def OnGUI():
        if GUI.skin.customStyles.Length > 0:
            Debug.Log(('Font name: ' + GUI.skin.customStyles[0].font.name))