It's two copies of "...where time becomes a loop." One on the left, one on the right. One of them is
slightly shorter than the other, so that as they repeat again and again, they slide in and out of phase. The track ends after they come back into phase.
If you listen to this with headphones, or speakers with decent separation, paying attention to this feels interesting. It's similar to the way listening to "binaural beats" can do interesting things to your brain.
Also if you are in the habit of putting an entire album on repeat and this is one of your favorite albums, then you've probably heard this a zillion times. If you have your music player set in "randomize by album" mode, then, well, it's the first track on this album, so every time it comes up you'll hear most of it unless you instantly decide you are not in the mood for Orbital 2, and even if you're not in that mood it may be pleasant to let everything come back into phase before going to another album.
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The next track on the album starts up entirely in the left ear, with a tinny, distant little loop, and the words "Even a stopped clock tells the right time twice a day". Once it brings in a deep bass, this bass is also doing some weird cross-ear phasing things.
And then the third track also opens with "Even a stopped clock..."; a theme has been established at this point. Time is a loop, and a stopped clock is right twice a day. The opening of "where time becomes a loop" is also a bit of a joke; Orbital's musical craft is very much about making a bunch of short loops that work together, and bringing them in and out over each other for four to seven minutes. Occasionally as much as thirty minutes, the extended version of "The Box" is glorious. This is something that utterly dominates most electronic dance music now, but Orbital was one of the first notable acts to really go hard on this, and this is their second album; they are saying "yes it's just more loops, we think they're good loops, enjoy!".
By the time you get to the last track, you've probably forgotten about Worf's repeated mantra. Especially if it's your first time listening to the whole thing and Halcyon + On + On just blew all the cobwebs out of your head. But Orbital returns to the idea, with two different loops that are very close in sound and length, played on both channels: "Input Translation"/"Output Rotation". They begin in phase with each other, drift out, and come back together. And the album is over.
Or, if you have the CD player on repeat (remember, this album is from a time when people bought CDs and probably stuck them into a one-disc player, maybe a 3 or 5-disc player if they were lucky, and the whole album is built with an awareness of this), you're back where you began, inputs translated and outputs rotated, and ready to be reminded of the Theory of the Moebius.
Time has become a loop. Come out of the trance Orbital has put you in. Do you want to experience this loop again? Does it feel rude to jump to another album before Worf's come back into phase again? You may as well let him get you back in sync with the moment the album began before going back into normal time.