Secure Sockets Layer/Transport Layer Security - encryption protocols that secure data transmitted over the internet. Like putting your messages in a locked box before sending them through the mail.
When you see 'https://' and a padlock in your browser, SSL/TLS is encrypting your connection to protect passwords and credit card information.
SSL/TLS is a protocol, not a single cloud service. These services manage TLS certificates (issue/import, store, renew) and integrate with load balancers, gateways, and CDNs to enable HTTPS.