It refers to the URL that will be made available to users to identify your site.,

URLs are displayed on the online ads that will help your site get recognized within different users. They are generally present in the last line of a given ad. The idea behind displaying URL is to indicate the users about the website they are likely to be taken on clicking the ad. There is a limitation to the number of characters that can be present in the display URL. The number is limited to 35 and the characters can not be extended onto another line. It is imperative that advertisers learn and understand different policies related to URL before submitting the ads