On my W-2, the box 14 is titled Other and underneath it has (c) RET. $2,136.18. Which is my retirement contributions. How do I enter this into my return?

Enter it in Box 14, just as it is shown of your W-2, with the first field in the row as "Other".

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 (e.g. Other.) 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.