A flexible spending arrangement (FSA) allows employees to get reimbursed for medical or dependent care benefits from an account they set up with pre-tax dollars. The salary-reduction contributions are not included in your taxable wages reported on Form W-2.
Under a typical FSA, you agree to a salary reduction that is deducted from each paycheck and deposited in a separate account. As expenses are incurred, you are reimbursed from the account.
As these salary reductions are the "contributions" to the account and are not included in your taxable wages on your W-2, you do not enter them as a deduction in your tax return. If they appear in Box 14 of the W-2, it is for informational purposes only (which you can verify with your employer).
When you run the program alerts under the Review section, you will be reminded of these Box 14 entries. This is to make sure people are aware that the amount will not go elsewhere in the return. If the amount does not need to appear elsewhere in the return, you can safely ignore this alert.