Maybe I can explain Redirect a bit more in detail.
If you have a blade configured to Block/Prevent something (Anti-Virus, URL-Filtering, whatever) the gateway sends a redirect to the client to show the blockpage. If this redirect is not followed by the client, then the action in the log is redirect, telling you that he didn't saw the block.
The reason for this that the blocked/prevented connection is either a background connection (not done by a browser) or a part of the page like advertisements, etc. and because of that not followed by the browser.