On the right side of the POS screen, there are 12 buttons--these are the POS buttons, and they exist to make life easier for you. Each button represents a function (for example, "Cash" represents choosing cash as the tender to pay for a transaction), and you can easily select one by clicking on it or pressing on it with your finger.
The 12 default buttons will automatically be assigned (you will see them on the right side of the POS screen), but you can re-create the buttons any way you choose. For more information on how to alter the POS buttons, please click here.
The 12 default buttons are:
Cash
Credit Card
Balance Card
Find Customer
Discount
Discount Lock
Refund Item
Refund Lock
Shipping
Find Order
Enter Product
Find Service