I couldn't quite figure out to do anything... "Group by" does nothing, and the docs say it takes effect when you use some aggregate function, of which I couldn'

I couldn't quite figure out to do anything... "Group by" does nothing, and the docs say it takes effect when you use some aggregate function, of which I couldn't find any? Would there be any advantage to using ruby or python in an interactive shell or jupyter-style environment? There are also some spreadsheet-like tools I've found useful, most of all https://openrefine.org https://openrefine.org.