Little Jack Horner was a character in an old nursery rhyme. The poem goes like this:
Little Jack Horner sat in a corner,
Eating his Christmas pie;
He put in his thumb, and pulled out a plum,
And said 'What a good boy am I!'
Now, let's break this down for easier understanding:
There was a little boy named Jack Horner who was sitting in a corner. He was eating a pie that was meant for Christmas, which is a time when people usually eat lots of yummy food.
As he was eating, he put his thumb inside the pie and pulled out a plum. Plums are a type of fruit that is small, round, and juicy. Jack was very excited to have found a plum inside his pie.
He felt proud of himself for finding the plum, so he said, "What a good boy am I!" This meant that he thought he was a good boy for finding the plum in the pie.
In summary, the nursery rhyme is about a little boy named Jack Horner who found a plum in his Christmas pie and felt proud of himself for it.