Frations are a way of knowing if your pie is cut up into quarters halfs or wholes.
This is a video about fractions for kids. It explains about denominators or numerators and halfs and stuff like that.
These are some pies. The one in the middle has 12 pieces, you could use that with division to share it equally with other people. For example you could divide it by 4(to create it into 4 that four people could eat.