That's a general concept, so you can just run a Google search, first hit:
What is slice and dice? - Definition from WhatIs.com
To slice and dice is to break a body of information down into smaller parts or to examine it from different viewpoints so that you can understand it better. In cooking, you can slice a vegetable or other food or you can dice it (which means to break it down into small cubes). One approach to dicing is to first slice and then cut the slices up into dices. In data analysis, the term generally implies a systematic reduction of a body of data into smaller parts or views that will yield more information. The term is also used to mean the presentation of information in a variety of different and useful ways.
This term can be compared to drilldown , which is the process of dividing an information area up into finer and finer layers in a hierarchy, but with the purpose of narrowing in to one small area or item.
Another one:
What does Slice and Dice mean?
If you think of your data in charts as a cube, with dimensions as axes and expression as small dices, the concept and analogy should be more clear, especiall when using a drill down group like Year - Month - Date.
