The Manchester United legend, who will also continue as number two to Martin O'Neill with the Republic of Ireland, has been keen to make a return to the day-to-day workings of football since being sacked as Ipswich manager in January 2011.
Keane, having also been in charge at Sunderland, insists he has no problems being an assistant.
"From my experience so far alongside Martin I am a bit more hands-on with the players, which I have enjoyed," he said. "It is a different role with Villa but I can adapt and I think my experience as a manager will help because it is tough being a manager.
"Hopefully I will make Paul's job easier. Hopefully I am someone Paul can trust; talk to the players and staff.
"I have some good experience from my playing days - some bad ones as well.
"I'll keep my job description pretty simple. I'm here to help the team and get results.
"I have some good experiences as a player and a manager and obviously he (Lambert) thinks I can bring something to the party.
"I am not promising miracles but hopefully an improvement."
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