The Yor are a robotic race that need to build new Yor to grow, as opposed to organic life that grows based on food.
However, there is a bit of ambiguity in their building options in that "Manufacturing Yor" is a building that increases production (but does not, as could be mis-interpretted, build Yor population). The item to "build" that actually builds Yor is simply called "Assembly."
While those of us who play the game for awhile understand this (and/or understand you should always mouseover something if you aren't sure), I think the ambiguity is offputting. Its actually sloppy phrasing -- if the "Yor" in Manufacturing Yor is meant to be an adjective and not a noun, it should precede the verb so it reads "Yor Manufacturing." Substitute "American" for "Yor" and I think its easier to see -- "Manufacturing American" literally means building an American as the product being manufactured whereas "American Manufacturing" specifies Manufacturing done /by/ Americans.