What is the information in the leftmost two columns and how do I turn it off?

[M. Edward (Ed) Borasky]

I recently updated to vim 7.0 on a Gentoo Linux system. Since then, 
some, but not all, of my editing sessions start out normally. After a 
second or two, though, the file is shifted right two columns and numbers 
appear in the first column and ">" signs in the second column. What does 
this mean? How can I turn it off?