The check box enables / disables constant scanning of websites.
If the check box is selected, Web Protection scans websites before they are opened with the help of the Kaspersky Security Network cloud service that contains information about the reliability of files, apps, and web resources. Depending on the scan results, Web Protection opens reliable websites and blocks malicious websites designed to distribute malicious code, and spoofed (phishing) websites designed to steal your confidential data and gain access to your financial accounts.
If this check box is cleared, Web Protection does not scan websites.