This message is telling you that there may be both secure and non-secure content on the page. Secure and non-secure content, or mixed content, means that a webpage is trying to display elements using both secure (HTTPS/SSL) and non-secure (HTTP) web server connections.
Internet Explorer blocks non-secure content by default and is set to prompt you when this is happening. Changing this setting may make your computer vulnerable to viral, fraudulent or malicious attacks. Adweb does not recommend that you attempt to disable this setting. We recommend you to contact your web developer / website owner and make sure the complete content of the website is served over https.