...
btn2=Button(
root,
command=KHB,
text='Ножницы',
font='Arial 20'
)
btn3=Button(
root,
command=KHB,
text='Бумага',
font='Arial 20'
)
btn1.place(x=50,y=350,width=250,height=100)
btn2.place(x=375,y=350,width=250,height=100)
btn3.place(x=700,y=350,width=250,height=100)
root.mainloop()