How is the Bing Quality Score calculated?

The Bing Ads quality score shows you how competitive your ads are in the marketplace by measuring how relevant your keywords, ads, and landing pages are to customers' search queries and other input. The quality score can range from 1 to 10, with 10 being the highest.

Hello,
They explain it in great detail in Bing Ads help: https://help.bingads.microsoft.com