A second-hand shop is a shop which sells goods that are not new.
There are various types of second-hand shop, generally specialising in a particular type of merchandise.
People will sell used goods right in front of their home in what is called a "garage sale". The products would be set up in front of the garage.
In the UK, people buy and sell at a car boot sale. Sellers will drive their vehicles to a large field, laden with products both used and new, and sell out of their boot.