This statement seems a fairly straightforward observation: yes, it is true. There's not that much to be said about it directly.
However, it can tell us a lot about Shylock, and about Shakespeare. Look at the gap between words and emotion at other places in the play, including those spoken by Shylock. He should know that there is a gap between words and meaning, but here he seems not to. This may indicate a gap between how he sees spoken words and how he sees written words.
It also shows that Shylock has a kind of reverence for the written word. Perhaps this is Shakespeare's way of showing a dignity in his soul. Perhaps it is a suggestion of a religious attitude. It seems, though, to show Shakespeare's lack of real awareness of Judaism. There is a long tradition of laws requiring learned interpretation with Judaism, and Shylock should expect this.