In jack and Jill nursery rhyme What it mean Jill laugh at jack after his mom fix head with vinegar and brown paper?

It could mean that his mom wanted to care for Jack's injury with the materials that she had available.

Or, it could be a political or social commentary. When nursery rhymes originated, most people did not read and write, and books and newspapers were of little use to them. However, people were very clever. They made up rhymes to say to their young children which were really a way to avoid trouble with authorities or the better social classes while voicing their distrust, disgust, or other negative opinions of them. This is the reason that some nursery rhymes may not seem child friendly.