Where editors usually have editing shortcuts, vim has an editing grammar.
So you can copy (or select, or replace, or delete, or any other editing verb) N arguments or blocks or lines or functions or any entity for which vim has an editing noun, or around or inside either of these, and you only need to remember a few such editing verbs and nouns and adjectives in order to immediately become much more effective.
It's so effective that switching back to a regular editor feels annoyingly clunky. (I guess that's why many offer vim plugins these days.)
Better: you can record entire editing sentences and replay them. Ever had to make the same change on dozens of lines? Now you can do it in seconds.
Now of course, replaying a sentence, or several sentences, is also a sentence of its own that you can replay in another file if you want.
It's neat. :)