You know when you go shopping, either online or offline, and you get the shirt in your hand, you look at the label and it tells you the materials it was made of? Well, Google is testing showing you that information before you buy, before you even click to buy, directly from the Google Shopping ads at the top of the web results.
Here is a screen shot from Jackson Lo on Twitter (click to enlarge):
I cannot replicate, I see everything Jackson sees minus the materials section.
I guess this is one of many tests. But I do not see the "Ad" label, I see the "sponsored" label like he does in this screen shot - I thought Google was changing that soon.
Forum discussion at Twitter.