With some experience and the right mindset, Vim's language becomes second nature and a mapping like yours is very easy to understand.
The thing is that too many people, me included at the beginning, follow the "learn -> customize" path in the wrong order: "customize -> learn"; often because of articles like this. This lead to a non-productive mix of plugin-addiction and mappings-dependance that's rather obviously counter-productive.
The ideal path would be to first learn how to use plain Vim then use this knowledge to customize it. This path leads to a short .vimrc and a lightweight .vim directory while the other leads to a miles-long arcane .vimrc and a bloated .vim directory.