SSL Certificates are used to mark your website with ‘HTTPS’ – this alerts Google that your website is secure and care securely performs transactions.
Websites that would not have SSL Certificates (and thus, would not have HTTPS on their URL) are marked down by Google and entry might even be restricted!
SiteLock however is a safety software for safeguarding your website (s) from malware and viruses. SiteLock is a third-party service and a few internet hosting firms depend on them to offer their prospects online safety.
SSL Certificates and SiteLock are each paid options on most hosting platforms. From critiques, I’ve seen that SiteLock typically doesn’t shield the websites of shoppers to those net hosts successfully and leaves many wanting.