The salon runs out of the purple shampoo on a Saturday. Someone notices at 3pm, the rep is not back until Tuesday, and three clients who would have bought a bottle go home without one.
Square or the salon's till records every retail sale. The system reads those sales each night, takes them off a stock count kept in a Google Sheet, and watches the number. When a product drops to its reorder point, a level the owner sets per product, a reorder email is drafted to the supplier in the owner's own Outlook with the product codes and quantities filled in. It sits in drafts. She sends it on Monday morning, or does not, if she knows the line is being discontinued.
Deliveries go in the other way. When an order arrives, she types the quantities into the same sheet, or forwards the delivery note and the numbers are read off it.
Once a month a line in her Monday email says which products sold nothing. That is the stock to stop buying.
This is the kind of thing we build. It runs in your own till and your own email.