Depending on what part of the world you're in, your screen will look slightly different at this point.
The PC/PS/Allowance buttons allows you to designate those items as such and will bring those items into a separate area of the quote letter and tag those items on the "Actual Costings" tab of the Job Management section.
When you select the PC/PS/Allowance items, it will change how the markup is distributed in the quote. Read more about that here:
Australia and New Zealand
Adding a PC/PS item
Displaying a PC/PS item
See this article here:
Changing/settling a PC/PS item
North America
Adding an allowance item
Displaying an allowance item
See this article here: