rpg code he

#game
#im not great at python but im trying to practice for my gcses lol!!
import random

xp = 0
lvl = 0
levelNext = 5


def var():
    global xp
    xp = 0
    global lvl
    lvl = 0
    global levelNext
    levelNext = 5


def starter():   #displays basic char
    name = input("What is your name?")
    print("**********************************")
    print("**********************************")
    print("Your name is", name,"!!")
    print("You have 0 skill points currently.")
    print("You are currently unranked.")
    print("You have no weapons avaliable.")
    print("**********************************")
    print("**********************************")

def levels ():   #level system?? when i call it it says the variables xp and lvl are not defined and im super confused!!
    while xp >= levelNext:
        lvl = lvl + 1
        xp = xp - levelNext
        levelNext = round(levelNext * 1.5)
        return lvl


var()
starter()
print(" ")
print(" ")
print("Maybe if you train you could improve your skill..?")
action = int(input("What would you like to do? 1. Train"))
if action == 1:
    print(" ")
    print(" ")
    print("You do some push ups, but you can only do 5 before giving up.. You gained 5xp!")
    xp = xp + 5
    levels()  #error here
    print("                   ")
    print("                   ")
    print("Well done, you have reached level",lvl,"!!")