Great question, you will see this on all product listings.
It is simply a social share button, but the idea is that if you like a seller or an item we encourage you to pay the item forward.
The reason being is, is not only are you doing a great service to the creator but you are potentially sharing with your friends an item that they may like.
Not only are you helping the creator, but you are helping each and every person who wants that product. There is no personal gain from doing so, it's merely an act of kindness.
We encourage you to use it as much as you please.