High quality ratings for an ad can:
increase its average cost-per-click (avg. CPC) bid
be achieved with an increase in bid
improve its position
increase how often people click on it
Quality Score is an estimate of the quality of your ads, keywords, and landing pages. Higher quality ads can lead to lower prices and better ad positions.
Read more here: https://support.google.com/Google Ads/answer/140351?hl=en