My mother's new power of attorney has my brother as her agent, with full power of substitution and revocation. Does anyone know what this means?

As far as I know this means he has the power to do everything for you mother when it comes to financial matters. He could name a substitute POA and revoke his own POA appointment. You should check with an attorney to clarify/confirm this as I'm not a legal expert.
Carol

Hi Carol, thank you. Actually my daughter is an attorney and she got back with me on this. Yes, he can appoint a substitute POA and revoke that attorney. He can always revoke his appointment. I think this wording is to give him power to let someone else do his duty for him in case he is not available. However, if he dies or just resigns, I am the alternate. However, they spelled my name wrong on the document (and this is my family) so who knows. These legal documents need to accurate, but this has been like pushing a rope up hill to get my mom to do anything. We will see. Thanks