Instead of a description, we'd rather give examples from life:

Option 1. The owner of a small store (stall) makes the purchase of goods.
The owner goes on the market makes a lot of small purchases. It is convenient for him, because he easily scans a product that has a bar code, a product without markings (fish, raw meat, vegetables, fruits), he simply takes pictures. All this is automatically folded into a sign. At the end, he sends a report on his purchases to an accountant who automatically puts everything into the accounting program (for example, 1C, Dedodod, Debit Plus, a warehouse, etc.)

Option 2. The hotel owner sends the driver (administrator) to make a purchase.
The driver visits the market to buy flowers, vegetables, fruits, eggs and other products for breakfast. He photographs all these products in the program, indicates the price and quantity. Then he calls in a supermarket and buys household chemicals, in the supermarket he scans bar codes. Upon arrival at the hotel, he already has a report on the money spent for the hotel administrator.

Option 3. You are the owner of a fashion boutique.
A boutique owner selects a collection for his store. He sits on the presentation and selects the clothes. Models pass by him, he quickly makes a photo of a favorite thing in the program, records the price and the name of the supplier. After the show, he opens the excel spreadsheet and, in a relaxed atmosphere, once again analyzes what he saw.

Option 4. You are a seller in the market.
The buyer asked for an invoice with photos, names and prices. You instead of writing a long list on a piece of paper in the program entered the price, quantity + quick photo. At the end of the file print or send to the buyer on viber, email, skype, whatsap.