These are just a dump of the .lproj/.strings on an OS X/iOS system. So technically, Apple owns the copyright on them, and this app is merely presenting them for educational purposes. Also, the licensing is dubious at best.
I was thinking "why the hell isn't this a web app?", but that makes sense.
EDIT: Rogue question mark. I'm Ron Burgundy?
Microsoft provides standardized terminology collection in different languages, which is useful for UI translators
http://www.microsoft.com/Language/en-US/Terminology.aspx (e.g. it's useful to know whether Microsoft translates "Start" button to Russian as "Старт" or "Пуск" -- without knowing the exact term, most translators will probably choose the former, while MS uses the latter).
I guess this app wants to provide similar collection, but for Apple's terminology.
You can look at the strings, but thou shalt not use them or even memorize them.