Can someone tell me what i did wrong in my code?

This is the Code its a KG to LBS calculator in python:

import tkinter as tk 
from tkinter import ttk 
import ttkbootstrap

#funkcja do przeliczania

def przelicz():
    kilogram_input = input_string
    funt_output = output_string
    funt_output = kilogram_input * 2.204
#tworzenie okna 
okno = tk.Tk()
okno.title('Nowe Okno')
okno.geometry('500x250')

#dodawanie rzeczy
label = ttk.Label(master=okno,text = 'Kilogramy na Funty', font='Consolas, 40')
label.pack()

input_string = tk.IntVar()
input_label = ttk.Entry(okno, textvariable=input_string)
input_label.pack(pady=15)
button = ttk.Button(okno, text='przelicz', style='info', command=przelicz)
button.pack(padx=10)

output_string = tk.StringVar()
output = ttk.Label(master=okno, text = "", font='Consolas, 30', textvariable=output_string)

#uruchamianie
okno.mainloop()

SORRY FOR USING POLISH LANGAGUE.

When I try to calculate the mass i see an errors.
funt_output = kilogram_input * 2.204
~~~~~~~~~^
TypeError: unsupported operand type(s) for *: 'IntVar' and 'float'

You're trying to multiply an IntVar object with a float number (2.204). You need to retrieve the value stored inside the IntVar before performing the multiplication. Also, you change from IntVar to DoubleVar to accept floating point numbers.

I tried this and it's working well

import tkinter as tk
from tkinter import ttk
import ttkbootstrap

# function to convert kg to lbs
def przelicz():
    kilogram_input = input_string.get() 
    funt_output = kilogram_input * 2.20462  # convert kg to lbs
    output_string.set(f"{funt_output:.2f} lbs")  

okno = tk.Tk()
okno.title('Nowe Okno')
okno.geometry('500x250')

label = ttk.Label(master=okno, text='Kilogramy na Funty', font='Consolas, 20')
label.pack()

input_string = tk.DoubleVar()  # IntVar to DoubleVar to accept floating point numbers
input_label = ttk.Entry(okno, textvariable=input_string)
input_label.pack(pady=15)

button = ttk.Button(okno, text='Przelicz', style='info', command=przelicz)
button.pack(padx=10)

output_string = tk.StringVar()
output = ttk.Label(master=okno, textvariable=output_string, font='Consolas, 20')
output.pack(pady=15)

okno.mainloop()

Because input_string is an instance of tk.IntVar(), you need to call get() on it in order to retrieve the value stored in the variable

(really, input_string should be a tk.DoubleVar() to allow for floating-poing (decimal) values)

You'll see a similar issue with output_string, where you should use set() to update the value

You can then pare down the function przelicz like so:

def przelicz():
    output_sting.set(input_string.get() * 2.204)