There is a Favors building on the map. There you can find the items you can purchase with these game units. 

These items look pretty, but there is more to them. Once you complete a set, these items will give you a huge bonus! You can see what the bonus is on the items page. 

You get Favors from leveling up celebrities. You get the chance to get Favors from completing Catering orders.

You get Golden Favors from completing League Tasks. For this, you need to join a Cafe Club or create one. For more info on that, you can visit the Leagues help article.