"S" in HTTPS indicates a secure site. If you visit a web site or web page, and look at the address in the web browser, it will likely begin with the following: http://. This means that the web site is talking to your browser using the regular 'unsecured' language. In other If you fill out a form on the web site, someone might see the information you send to that site. This is why you never ever enter your credit card number in an http web site! But if the web address begins with https://, your computer is talking to the web site in a secure code that no one can eavesdrop on.
If a web site ever asks you to enter your credit card information, you should look to see if the web address begins with https://. If it doesn't, there's no way you're going to enter sensitive information like a credit card number!
