Decrease CTR rates as users are sent to specific pages of your site
Show your business address, phone number, and a map marker with your ad text
Allow targeted remarketing list users to land directly on specific pages of your site
Allow advertisers to give users the option to land directly on specific pages of your site
Sitelinks can take people to specific pages on your site—your store hours, a specific product, or more. When someone clicks or taps on your links, they skip right to what they want to know or buy.
Read more here: https://support.google.com/adwords/answer/2375416?hl=en