I am a NE resident that worked in AZ over the summer and on my W-2 for that company in AZ I have an amount in box 16 for NE but why there is an amount there?

Did you work in NE during the year?

Yes I did, I haven't received the W-2 from that company yet. So I am unsure why the company I worked for over the summer has an amount here, since my time with that company was spent solely in Arizona.

What words indicate that the amount in box 16 is specifically for NE?

Box 15 for state says NE and its on a separate section of the W-2 that says NE State Filing Copy. For the AZ State Filing Copy box 16 shows the same amount in box 1 with AZ in box 15.

You will claim a credit for income taxes paid to Arizona on your Nebraska income tax return.