What does the code "YC" in Box 14 of the W-2 mean for Category in TurboTax?

Box 14 of the W-2 is an informational box only. Rarely is the data in that particular box used in figuring your taxes. There are no hard fast set "codes" for box 14 (like there are for box 12). So you'll need to ask your employer or issuer of that W-2 what it means.  In the Instructions for box 14 it states:

Box 14. Employers may use this box to report information such as state
disability insurance taxes withheld, union dues, uniform payments,
health insurance premiums deducted, nontaxable income, educational
assistance payments, or a member of the clergy’s parsonage allowance
and utilities. Railroad employers use this box to report railroad
retirement (RRTA) compensation, Tier 1 tax, Tier 2 tax, Medicare tax,
and Additional Medicare Tax. Include tips reported by the employee to
the employer in railroad retirement (RRTA) compensation

Since there’s no standard list of W-2 codes for box 14, employers can list any description they choose. 

• Contact your employer as to what the W-2, Box 14 code "YC" is being used to report.