It means the check was rejected - presumably for insufficient funds. Ask the bank.
We don't know. You need to contact your employer and ask why the check was returned. They should pay the fees you are charged.
Soo I recently deposited a check from my employer to Bank of America. It went through immediately, but two days later the money was taken out and it now says "return item chargeback". I have never had any problems with a deposit so I have no clue what to do in this situation. I talked to some coworkers and their checks went through.