HTTPS means your website is safe. Converting your website to HTTPS means your site can be trusted, your visitors' information is safe and the content on your site is legitimate. HTTPS requires obtaining an SSL certificate for you site. The SSL is website specific, can not be transferred and must be purchased yearly. Regardless if you sell goods online, everyone needs an SSL - it has been "required" for SEO rankings and soon, sites without an SSL will be flagged as an "Unsecure Site."
Russ and Randy
All the best!