Looks more like a fence to me, but whatever.
Are you serious? It has the same function as a wall. It is there to keep people out.
Well, not to be on Ryan's side, but...
technically it is a fence. According to Wikipedia:
A fence is a structure that encloses an area, typically outdoors, and is usually constructed from posts that are connected by boards, wire, rails or netting. A fence differs from a wall in not having a solid foundation along its whole length.Ryan's fence: