The Shop Manager has only one function: Managing Shops. There is only one custom block for this behavior, which will open a shop, so let's look at this block in detail.
Open Shop Window with Items: <list> Buy Only <boolean> Sell Only <boolean>: This will open a shop with the given list of items and will either set the shop to Buy Only, Sell Only, or allow the player to buy and sell. The list function accepts a list of items/weapons/armors. More info can be found here.