A ruana is a poncho-style outer garment or wrap. I found this sheer blue animal print one on sale at Chico's a couple of years ago.
I like the fact that this one is sheer and can be worn in a variety of ways as a bit of cover when you want to dress in cool sleeveless tops and white ankle pants or Capris. (Ruanas are also great for winter in fabrics such as wool and cashmere.)
As you can see there isn't much construction to a ruana but they are so versatile.
This is my favorite way to wear them in both winter and summer. I think they look so chic!