The Irishman's temporary move from the MLS club is expected to go through by this weekend.
Although it is only a short-term deal, McLeish believes the striker's qualities will have a big impact on the club.
"We are talking about a guy who is at his peak," said the Scottish manager.
"He'll bring his experience, his enthusiasm as a footballer, leadership that can help in the dressing room and obviously he can score goals. His movement is great and he can hurt defenders with it.
"The Irish boys have the tournament to look forward to and Robbie wants to be at his very best. That sort of motivation can only be good for us."
Should the deal go through, Villa will be the 10th club Keane has played for in his career.