SSL stands for Secure Sockets Layer and, in short, it’s the standard technology for keeping an internet connection secure and safeguarding any sensitive data that is being sent between two systems i.e the user and the website owner.
A website SSL can be quickly identified by looking at that URL of the website on Chrome or another major web browser. Where you should see a Padlock beside the URL.
Without SSL somebody can spy on communications between the website and the user potential stealing passwords and credit card details.
Along with security issues no SSL will negatively impact your ranking on google and other search engines.
SSL can be installed on any website however many hosting companies lock it behind a pay wall.