The section includes rows that highlight your recent channels as well as individual genres, including live news and sports. You can favorite channels to be sure they take priority in any given row.
The new tab will reach all American Fire TV users over the course of the next several days. It’s not a channel guide (there’s already an equivalent for Amazon Prime Channels users), so it won’t quite replace the browsing experience you might be used to from conventional TV. However, that’s not necessarily a problem. It might do the trick if you’re a cord-cutter who just can’t wait for an on-demand video to start watching.