To answer your questions:
- The web page you're viewing is being served over SSL (https). However, it includes resources, possibly images, scripts, etc. that aren't being sent over a secure connection. This message occurs to warn you that the page might not be as secure as you think it is. This type of message has been around for a long time. I remember seeing it way back in the Netscape 3 days (circa 1998).
- The way to fix is is to contact the owner of the page in question and ask them to fix their page. Of course, if you have any extensions that might be pulling in additional stuff, you'll need to disable those extensions and try again before bothering the site owner.
Since you're getting this on opening a new page, extensions seem like a possibility, in which case you'll have to track down which one is responsible.