To bring home the bacon is to earn a living. You might bring home the bacon by working nights at a warehouse and as a school crossing guard by day.
There are a lot of guesses about the origin of this phrase, some of them going back to twelfth century England and various traditions and sayings involving bacon. However, to bring home the bacon seems to be a much more recent idiom. The mother of American boxer Joe Gans, in a 1906 telegram in which she urged her son to win a difficult match, made the first recorded use of bring home the bacon, encouraging him to do just that.