Your connection is not private?

Okay so this comes up when I go to some sites such as Google and Facebook. I have been googling (on my iPhone) what the solution is and people say to check the date and correct it but my date is correct, so what do I do?

By the way, I'm not at all good with computers so if you do know a solution keep it worded simply.

I appreciate the help, thanks.

If you have a VPN installed it might tell you that if it's turned off or if it's not set to your home network or in a public router or place.