Once you have enough you can buy various items - fast cars, big houses even a rowing boat (not joking).
Once you've bought these things you'll see them against your profile. Each item is listed in a category - cars, boats etc are all grouped together in their own group, so all cars are together, boats together etc.
Each category has a special "badge" which appears next to your trader name once you have bought all the items within it.
So for example once you've bought all the paintings and artworks items you'll earn the " Art Critic" badge.