What it means
TLS can protect data in transit and authenticate a server name through a certificate system. It does not prevent an authenticated endpoint from reading the data it receives.
For hosting
Use supported protocols, correct certificates and automated renewal with monitoring. HTTPS is necessary for many services but does not fix an insecure application.
Who reads the data after decryption?
The endpoint terminating TLS can normally access plaintext. Review reverse proxies and external APIs as well as the browser-to-site connection.