Understanding tkinter Treeview

I am trying to create a Treeview - here is my code:

def treeview(self):
        tree = Treeview(self.parent, columns=("no","name","props","subs", "summary"))

        tree.heading('#0', text='No.')
        tree.column('#0', width=100)
        tree.heading('#1', text='Name')
        tree.column('#1', width=100)
        tree.heading('#2', text='Props')
        tree.column('#2', width=100)
        tree.heading('#3', text='Subs')
        tree.column('#3', width=100)
        tree.heading('#4', text='Summary')
        tree.column('#4', width=100)

        tree.place(relx=0.5,rely=0.2, anchor=CENTER)

There should be 5 columns - However, there is sixth blank column to the right of the last column. Why is this?

Also, how do I actually add text to each column? Thanks!