Can anyone please tell me, what is the use of social media to get rank high on Google
Google takes into account social signals when ranking a website. This includes how much your website's content gets shared, the amount of followers you have, and the amounts of likes/favorites you have.
Google uses this ranking algorithim because unlike other ranking factors, social media can accurately guage a website's interaction and popularity among its fans/users. This means that if you have quality content and an active user base its probably worthy of your site being higher in the SERPs because you are providing value which is something that Google has been valuing now for the last 18+ months pretty heavily.
Digital marketing is so persistent that customers have accessibility information any time and any place they want it. Gone are the days when the information individuals got about marketing came from you and contains only what you desired them to know. Digital marketing is an ever-growing resource of enjoyment, information, purchasing and social connections, and customers are now revealed not just to what your company says about your product, but what the press, buddies, family members, colleagues, etc., are saying as well. And they are more likely to believe them than you. People want manufacturers they can believe in, companies that know them, emails that are customized and appropriate, and provides designed to their needs and choices.
apart from the traffic you'll get most links put in social media like open facebook groups, tweets and so on, even if they are no-followed they will count as social signals and definitely help with your rankings. This will happen over time though, don't expect to spam a few hundred posts on facebook and jump to the first place.
Google nowadays focus on connection and interaction more than ever. Through shares, mentions, hashtags, likes, comments, Google recognizes various brands. The more the interaction that is happening, the more likely would Google make those brands show up on Google SERPs.