Python works with several graphical user interface toolkits, such as Gtk, Qt, and wx, but the default toolkit is Tkinter.
A basic example you can try:
from Tkinter import *
def Cumprimente():
hello.set("Olá, você!")
gui = Tk()
gui.title("Py5 - Python + Tkinter")
gui.geometry("400x300")
btn = Button(gui, text="Cumprimente", command=Cumprimente)
btn.pack()
hello = StringVar()
lbl = Label(gui, textvariable=hello)
lbl.pack()
gui.mainloop()
You can save this as an extension file ".py" in Idle and run through it (F5).