Complex sentence: Auctionair.co.uk is an online retailer based in the UK operating a sealed-bid auction (or "Blind Auction") system where bidders cannot see what others have offered.
Split into simpler sentences: Auctionair.co.uk is an online retailer based in the United Kingdom. It is operating a sealed-bid auction (or "Blind Auction") system where bidders cannot see what others have offered.