Under a cafeteria, or Section 125, plan, you pay for your employer-sponsored benefits with pretax money. Your employer deducts your payments from your wages before withholding certain taxes. Your employer doesn't include your pretax payments in your taxable wages on your annual W-2.
W-2 Box 14 is for informational purposes only. It doesn't impact your tax return. It's Section 125 or a cafeteria plan.