"DI" is the usual abbreviation for Disability Insurance, typically a state program in which employers are required to participate. The PP#000-00000 is probably the employers policy or account number. If you want to add it and don't see any room, just fill in all the boxes you do have and "Tab" down - a new line should appear.
You don't need to add this to TurboTax in the W-2 interview - it won't affect your taxes.
Employers can put just about anything in box 14; it's a catch-all for items that don't have their own dedicated box on the W-2.
In TurboTax, enter the description from your W-2's box 14 on the first field in the row. Enter the dollar amount and select the correct tax category that goes with that description.
If none of the categories apply, scroll to the bottom of the list and choose Other–not on above list. Don’t worry. We'll figure out if it impacts your return or not. If we need more information, we'll ask you later in the interview.
On the other hand, if box 14 is blank, just skip over it. Don't enter a 0 for any blank boxes.
