Mysql – What Does LocalHost Return In Linux?

I wrote a Python program that users can send posts, signup and login. I used MySQL in this app. When I try to open MySQL with localhost it works, But when I insert my IP Address it does not work. I use Ubuntu and ifconfig returns a lot of addresses. I tried all of them but did not work. MySQL returns : Can't connect to MySQL server on (IP):3306' (113). What can I do?
Python code starting is like:

import tkinter as tk
from tkinter import messagebox
import mysql.connector

DB_HOST = 'My IP Address'
DB_USER = 'My User Name'
DB_PASSWORD = 'My Password'
DB_NAME = 'My Database'

# Connection Here : 
db_connection = mysql.connector.connect(
    host=DB_HOST,
    user=DB_USER,
    password=DB_PASSWORD,
    database=DB_NAME
)
db_cursor = db_connection.cursor()