This column shows the name of the portfolio bid strategy that's managing bids for your keywords, ad groups, or campaigns. If no portfolio bid strategy has been applied, the column displays “--”.
It Lets you choose how you want to pay for people engaging with your ads. Bid strategies for search campaigns include target search page location, target CPA (Cost Per Acquisition), target ROAS (Return On Advertising Spend), target outranking share, maximize clicks, maximize conversions, enhanced CPC and manual CPC.
REgarding to Facebook, It's the way you want Facebook to bid in the auction, based on your cost goals and your optimization for ad delivery. This will display as either lowest cost, cost cap, bid cap, target cost, highest value or minimum ROAS depending on your cost or ROAS control selection.