Tkinter2

from openpyxl.workbook import Workbook
import tkinter as tk
import pandas as pd

def saveinfo():
    valor1 = entry1.get()
    valor2 = entry2.get()
    valor3 = entry3.get()

    data.append([valor1, valor2, valor3])
    print(data)

def export():
    df = pd.DataFrame(data)
    df.to_excel("DataBase.xlsx")

def opennewwindow():
    global entry1
    global entry2
    global entry3

    window.destroy()

    newwindow = tk.Tk()

    tk.Label(newwindow, text="Please, enter data: ").grid(column=0, row=0, columnspan=3)

    tk.Label(newwindow, text="Number").grid(column=0, row=1)
    entry1 = tk.Entry(newwindow)
    entry1.grid(column=1, row=1)

    tk.Label(newwindow, text="Description", ).grid(column=0, row=2)
    entry2 = tk.Entry(newwindow)
    entry2.grid(column=1, row=2)

    tk.Label(newwindow, text="Brand").grid(column=0, row=3)
    entry3 = tk.Entry(newwindow)
    entry3.grid(column=1, row=3)

    tk.Button(newwindow, text="Save", command=saveinfo).grid(column=2, row=2, sticky='we')
    tk.Button(newwindow, text="Export", command=export).grid(column=2, row=3, sticky='we')

    newwindow.mainloop()

# --- main ---

df = pd.DataFrame
data = []

window = tk.Tk()
tk.Label(window, text="Platform").grid(column=0, row=0)
tk.Button(window, text="Choose an element: ", command=opennewwindow).grid(column=0, row=1)

window.mainloop()