The Bids column is displaying the amount of impressions that your specific campaign is bidding on and that also matches your campaign targeting criteria. Bids take into consideration different factors, including the geo-region you are targeting, banner sizes, contextual, audience and device targeting, and any other filter you could have applied to a campaign.
The Win Rate column is displaying the amount of Bids that you have won. This is determined largely by your bid price and your frequency cap. You only pay for Impressions won.
The number of impressions you’ve won, over the number of impressions you’ve bid on, is known as your Win Rate (%).