This has to do with the structure of a recurrent neural network, and artificial neural networks in general. The information can only flow one way in neural networks, so the arrow just goes that way (to the right) for purposes of the diagram, but all the arrows (highlighted below) could have just as easily been reversed — it’s just a technicality in the content. To be consistent with previous structures to the left however, I kept the middle arrows pointed to the right.

Cheers!