Whilst it is true that Google introduced having an SSL as part of it’s algorithm in 2014, unless your site is ecommerce or sends sensitive data across the internet you do not need an SSL and it will not significantly effect your Google rankings if you have one.
SSL or Secure Sockets Layer is a form of security you can add to your site which handles sensitive data such as personal information or credit card details.
An SSL costs between £25 and £150 per annum and should be installed by a web developer who knows what they are doing.
You can tell whether a site has an SSL, because instead of saying http://www…. in the address bar of your browser it will say https://www…. Many browers will also display a little padlock (SSL) or exclamation mark (no SSL)
It may be that Google increases the importance of having an SSL in its algorithm in the future, but right now there are more important factors to consider