I'm not sure about that, but from what I know it could mean 2 things:
- modularity of codes. Your codes must be capable to be separated into sections, functions, etc. If you need more info about program modularity, I don't think you are up for the job though :D
- slice multiple parts of one graphic and display it as if it's one. When a picture is too large, normally the designer cut it into multiple parts. This will make the loading faster and more user friendly. The problem with multiple parts is that there might be unwanted gaps / empty spaces between parts. The challenge is to make the gaps missing. I think this is slicing means.
and yes, like what UND3RDAW said, slicing is quite an old technique.