Congratulations on the new setup!
In addition to Sweetbeats' informative post about the Program outs letting you assign your channels to the tape deck with switches on the mixer instead of reaching back to re-patch cables on the back of the mixer, "bussing out" or "group outs" as it is known will also let you "submix" multiple channels down to fewer tape tracks: for example, if you wanted to record a drum kit that had six microphones on it, but you only had two tracks of tape left to work with, you could set up those six microphone channels on your mixer, but assign those channels to only two Program busses so all six drum mics would end up being "summed" to only those two tape tracks left. The catch to this is, of course, that you would be "printing" your drum mix to tape--so you would have to decide and commit to how you want those drums mixed together *before* you record them rather than being able to tweak and play around with the 6 individual mics come mix time after you're done recording, as you will of course only have control of the drum recording "as a whole" on just those two tracks doing it this way--it's a more advanced technique but it's a method sometimes used when you have more channels to record than available tape tracks and you're confident of how you want certain channels balanced--hence willing to give up some control over your sounds later during mixing.
I don't know if you're actually recording drums of if you ever want or need to submix your tracks, but I wanted to further illustrate your new mixer's capabilities. Cheers and have fun!
, but the signature is aimed at ME. 
