You can access this command in the Context Menu in View.
Some network resources will have their copies(local cache) in local disk after opened in browser. This will make it much faster when it is needed next time. Usually, those file types which will have local caches are pages, images, flashes, some of audios etc.
You can save local copies to specified position directly by this command. No need to download from network.
Notice: As shown in view, those Local Cache fields with the check box checked mean these URLs are local cached. And those ones not checked don't mean they are not cached. It just means that they are not cached before they are accessed not after that. You can right click on them and CooJah will check local caches again. If you local caches were found, the check boxes will be checked then.