list2.py

from tkinter import *
from tkinter import ttk
 
root = Tk()
root.title("множественный выбор")
root.geometry("400x300")

style = ttk.Style()

def selected():
    # получаем индексы выделенных элементов
    selected_indices = languages_listbox.curselection()
    # получаем сами выделенные элементы
    selected_langs = ",".join([languages_listbox.get(i) for i in selected_indices])
    msg = f"вы выбрали: {selected_langs}"
    selection_label["text"] = msg

 
languages = ["Python", "JavaScript", "C#", "Java"]
languages_var = Variable(value=languages)
 
selection_label = ttk.Label()
selection_label.pack(anchor=NW, fill=X, padx=5, pady=5)
 
languages_listbox = Listbox(listvariable=languages_var, selectmode=EXTENDED)
languages_listbox.pack(anchor=NW, fill=X, padx=5, pady=5)
languages_listbox.bind("<<ListboxSelect>>", selected)
root.mainloop()