You know, I'm not quite sure? The author writes under the assumption that the reader already knows what this is for. [Sypha briefly turns away from the refreshments to recover her spot in the book] Perhaps it says earlier on, I was flipping through at random.

[With one hand, she carves a chunk of softened apple onto her fork. With the other she outlines the silhouette of the array on the page.] I think it's...energy transference of some kind? There's a lot of scribbly little notes about how these shapes here buffer energy decay during the process.