As you improve the security of your website, you can encrypt the sensitive information changed between one device to another. This information can be anything from credit card details, to password or bank details.
When visiting a website, especially when submitting information or files through the server, the SSL makes sure that it’s the right website, and it goes to the right server. SSLs act as proof that this is indeed your website and not some imitation. It will help you against phishing sites that are trying to exactly imitate your website’s design and look to obtain sensitive information.