This feature is described more fully in chapter 25.
In quite a few languages, the nominal plural marker is identical to the (independent) 3rd person plural pronoun. This can of course be the case only in languages that have plural words. Identity means that there is only one word for the two functions, differentiation means that there are two words for the two functions, and in overlap, there are two words, whereby one form functions e.g. only as a pronoun and the other as a pronoun as well as a nominal plural marker.