Can some please explain what an ERS leak is and what repair costs? on 2000 Pontiac Grand Am

The service engine soon light came on in my Grand Am. I look it to Advance Auto to have it checked. The guy said it was an ERS leak. I can't find any info on this anywhere. I would like to know what to expect when I take it to the garage for repair. What they need to do, price range, and how long it will be down. He didn't give me the diagnostic code. Thanks.

Asked by for the 2000 Pontiac Grand Am
Gonna have to give us a code number on that one, have it checked again and post the code #.