Browser-Cache: deletes the files created when loading Internet pages in the Web browser.
Download-Cache: deletes cache-files created when files are downloaded from the Web.
Browser-Verlauf: deletes the list of pages that Web browsers keep to make pages load more quickly.
Letzte Suchvorgänge: allows you to remove the recent searches that the Web browsers store.
Web Page Previews: When you browse the web, Safari created a preview of each page like an image visible in the Top Sites page, the bookmarks and the history. This option allows you to remove all these images. When you restart Safari, a message will propose you to add previews from the webpages you’ve visited most recently.
URL-Icons: Many Web sites specify an icon (called a "favicon") which displays in the Address bar and alongside Bookmarks and addresses in the History menu. This option deletes the icons.
Formulardaten: The info that you type in the forms of Web sites are saved in a cache. This option delete this cache.
Cookies: Many Web sites store small files, named "cookies," on your computer, to make return visits easier; for example, it will spare you having to type your name and password when returning to a forum, etc. This option deletes those cookies.
Form values and cookies (may) spare you the typing of user-names, passwords and other required info when you revisit a web-form (as in forums, online-shops etc.). Use with caution!