Excel 2000

I am using an Excel spreadsheet that was exported from another program.
There is some kind of column to the left of my row numbers column with a
little 1 button and a little 2 button on top. Then there are dots at each row
down. Apparently the purpose is to jump to the last row where I have data,
because that is what happens when I click on 1 or 2. I can't see where it is
applied in View or Customize. I've looked through Help and can't find any
reference to what this feature is. Nor can I right click and get any
information on what it does or how to delete it. I want to eliminate this
column and don't know how.