Businesses, brands, and companies that use Facebook Pages can now tag products in their posts. Anyone who taps a tagged product is sent to another page with more information about it.
According to Facebook, only businesses and organizations that already have a product catalog or shop section on their Page can use the feature.

Shops that let you sell directly from a Page mean customers can complete the whole purchase without leaving Facebook. Businesses can build catalogs, split products into collections, manage orders, and run Facebook ads to promote items. Brands that treat Pages as a marketing channel still need to know their followers and when to publish what.
Product tagging is still in testing and may open a new door for product marketing. For now it is free. Facebook will likely find ways to monetize it later.