Did you receive two W-2s from this employer?
If so, does the other W-2 have amounts in boxes 1-8 (at least) but nothing in boxes 18-20?
If so, then just combine the two W-2s.
Boxes 18-20 are reported withholding for an income tax for a locality (city or county), and you would not normally see entries here unless there was also federal wages in box 1 (and in the other boxes).