efficiency usually means organization and speed. So if it is operationally efficient, it works very quickly and effectively.
skill means ability, or capability. Sometimes skill means that the ability is very good. For example, if you are good at doing something you can say "I am skilled at something." Operative skill would mean the ability to operate or do something well.
Sometimes, in English, we use phrases that sound very complicated. This type of language is often used to disguise really simple meanings or makes things seem more complicated than they are. I am not sure what context this came from, but it sounds like it came from a package. If it is in a scholarly article or a book, however, it is probably a reliable source. Please let me know if you need me to explain more!