What is the 5-minute renewal?

The seller has the option to set the auction to automatically extend if a bid is placed in the last 5 minutes.

If a bid is placed in the last 5 minutes of the auction, the expiration of the auction will be changed to 5 minutes again. This renewal may happen multiple times. If a bid is placed for the item in the last 5 minutes, the expiration time of the auction is always set to 5 minutes.