The secure from https isn't related to content on a website/service.
It is called 'secure' because theoretically the security protocols (ssl/tsl and some others) do not allow the information being exchanged to be easily understood (it encrypts the data flow), so, even if someone would catch your packets, they would have to decrypt it to understand the message.
Now this is useful because some information such as passwords, social security number, credit card number and etc. can cause a lot of problems if they are discovered by someone intent on causing damage.
In this sense, https helps us by making difficult for a third party to know what information we exchanged with a website (and that's why most banks do utilize at least https on their services), but that doesn't stop a website or service to be infected with malicious software or an attacker to indirectly reach you by infecting a server.
Now, I inferred from your question that when you used the term 'secure' you meant it in different way (in the sense of safety against malicious content), in this sense, https does not protect you at all because it doesn't pay attention to content (what is being transmitted through the connection) itself.