The House Of Swap is a small, two store building that houses a lot of different objects; it seems to serve as a trade store (people trade one thing for another).
However, in some episodes, we can see that Burt fixes some of the objects that are brought to the House of Swap. Therefore we can also infer that the House of Swap is also a repair shop for broken items. Then they get fix.
Very little is known about this shop; all we know is that it is run by Coop's Dad, Burt Burtonburger. It houses many types of items that people leave there and has been shown in more than one episode of Kid vs Kat.
In "Tickled Pink", Burt trades everything inside, even his clothing, for a pair of tickets to the monster truck rally.