"Several times, then, Lewis suggests that heaven will be a place where thinking and experiencing come together. On earth we think about what love is; in heaven Love is a Person we can experience. On earth we read books about many different things, especially God, on the one hand, while some of our experiences of Him are so intense that we cannot put them into words; in heaven the Divine Word speaks to us face to face in a language that lets us hear and say everything we never could before. In heaven to think a thing will be to do it; to do a thing will involve knowing it completely. On earth our words are abstract thoughts that never quite say everything we want them to. In heaven language is a person, and to communicate will be to offer everything we are and to receive back every thought, feeling, and meaning from those with whom we share words".
I've read several of Lewis's works (Narnia series, Great Divorce, Mere Christianity, pieces of a few others), and I'm not aware of any of his writings that suggest what that author describes.
Certainly, Lewis had some very interesting views about what life will be like after we die (or after the return of Christ). In The Last Battle, "heaven" is depicted as a place that is ever increasing in meaning and depth - like an onion, which you can peel layer by layer, and each layer is deeper than the previous, except that each new layer is bigger than the one before.
In The Great Divorce, he develops the idea that realness depends on our proximity to God. Thus, people closest to God (ie, in heaven) are most real, but those furthest are the least real (ie, in hell).
But, although those ideas are certainly very imaginative and abstract, I don't think he ever suggested that heaven would be so unlike our current existence that even things like thinking and acting become conflated.
As I understand, Lewis's goal was to portray the idea of eternity as something that is infinitely good, in a broad sense - it is infinitely "real," infinitely large, and has as its infinite climax the enjoyment of God himself. It would take a finite being an eternity to fully explore such a place, and I think that was his point. The idea is that there will always be more to see, more to explore, more to enjoy (thus, the "layers" from The Last Battle). And not only is there always more in the sense of joy, but also in the sense of substance, thus the portrayal of people becoming more "real" in The Great Divorce.
But, I don't think it would accurate to say that Lewis's views meant that one abstract concept (such as language) would some how transform into a concrete concept (like a person), like that quote suggests. Lewis did use abstract concepts in bizarre ways, but not because he was trying to communicate that heaven is a strange place where concepts are in some perpetual state of moving back and forth between abstract and concrete. (Imagine the absurdity of suggesting that a person would be a language, even though the article suggests the converse - language will be a person. And if language is a person, what language would I use to speak with him?)
Lewis was simply trying to use creative examples to make his point: heaven is a place that is so good (in the broadest sense possible) that it will take us finite creatures an eternity to explore (or, in other words, we will never run out of new and better experiences).