Please explain baseball lines seen in newspapers to me

[jtg51]

I understand the basics of sports betting, but I have no idea what the baseball odds commonly listed in newspapers mean. The odds I'm talking about look something like this:

Favorite Odds Underdog
Yankees 11-13 Orioles
Red Sox Even-6 Blue Jays

I've been asking around lately, and a lot of people, including some who know a lot about sports betting, have no idea what that means. Does anyone or is it all a big joke?