Box 14 information does not affect your tax return. Information entered in box 14 does not transfer to other places on your return. Depending on what the item is you may enter the amount in other places on your return manually.
If the information in box 14 matches a category in TurboTax you would just enter it there in the W2 topic.
If, however, you don't find a matching category, you can use "other (not classified)." An item that you may find there, for example, is a donation to charity which you also enter in the charitable donation topic in "Deductions & Credits".
Most of the time there is nothing else to enter as it is purely informational.