Chest shops are used for selling and buying items to other players, mostly used for bulk item selling/buying.
Just right-click the sign to buy, left-click to sell. If the chest is full, or you don't have the item in your inventory it will tell you with a chat message. If you own a chest shop, it will notify you when someone is selling items to you or when your chest shop is out of stock.
First, place either a chest, barrel or shulker down. Then place a sign on the container. On the sign, write: First line will be automatically filled with your name by the plugin, so leave that blank. Second line is the amount of items to buy or sell. Third line is a combination of buy and sell prices. You need to have a price indicator (like 'B' - price that will apply to items BOUGHT by PLAYERS - or 'S' - the SELL price) near the price - the prices are separated by a colon (:). The forth line will hold the id/name of the item. Write ? on the sign and the item will be auto filled with the one from the chest or you can click on the sign with the item afterwards. Optionally you can put the actual name on it. You can find out the name of the item you're holding by doing /iteminfo
For example: A person can buy 64 blaze rods for 10 dollars and sell them back for 5 dollars from Biliap.
/cstoggle Command to turn on/off messages from your shop(s). Will still notify you when a chest shop is empty.
/iteminfo Get information about the item in your hand.