def PopUp():
        pop = Tk()
        count =output1.split()

        for  i in range(0,len(count)):
                var=[]

                l=Checkbutton(pop,text=output1.split()[i],variable=var.append(i)).grid(row=i+1,sticky=W)

Output:
x  ABC
x  CDE
x  DEF

import tkinter as tk


class MainFrame(tk.Frame):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.checkbuttons = {'ABC': tk.IntVar(),
                             'CDE': tk.IntVar(),
                             'EFG': tk.IntVar()}
        
        for key, value in self.checkbuttons.items():
            ctrl = tk.Checkbutton(self, text=key, variable=value)
            ctrl.pack()
        
        self.button = tk.Button(
            self, text='Checkbutton values', command=self.on_button)
        self.button.pack(pady=15)
        self.pack()

    def on_button(self):
        print('checkbutton values')
        for key, value in self.checkbuttons.items():
            print(f'{key}: {value.get()}')


if __name__ == '__main__':
    app = tk.Tk()
    main_frame = MainFrame()
    app.mainloop()