Optimization score is an estimate of how well your Google Ads account is set to perform. Optimization score runs from 0% to 100%, with 100% meaning that your account can perform at its full potential.
Along with the score, you’ll see a list of recommendations that can help you optimize each campaign. Each recommendation shows how much your optimization score will be impacted (in percentages) when you apply that recommendation. Applying or dismissing these recommendations changes the overall optimization score of your account. Optimization score is available at the Campaign, Account, and Manager Account levels.