Bid History for an item gives you information about every bid placed on an item, who the bidder was, the amount they bid, whether it was placed using a Proxy Bid, and what time the bid was placed.

To view the Bid History for any item, go to Items > Item Management > search for the item in question > click on the corresponding number in the 'Number of Bids' column

If you were to click on any of the bids/bidders, this would be an alternative way to get to their profile within Bidder Management.