Deciphering for people who are interested in Audio Engineering:
We're most likely dealing with a concert situation here. TheWynner is speaking to his intern who is controlling the mixing-console.
The audio signal flow would be: Stage (Band is playing) -> Mixing Console (That thing with thousands of knobs) -> PA (Public address system, or loudspeakers for normal people)
Another possible situation is that TheWynner is talking about a Studio-Recording. But that seems unlikely because you normally wouldn't put that much processing (EQs, Limiters) on the signal before recording it. You can do all that in Post-Production. But you would still be concerned about clipping. More about that in a second.
First off, you're clipping the output bus so check your gain staging and ensure you have good signal to noise but still have headroom.
When you are in a concert situation, all the signals (electric signals) coming from the stage (singer's microphone, guitarist's guitar, drummer's microphones) are coming into your mixing console. The mixing console's job is to combine all these signals into something that sounds good when played back by the PA. Here we are dealing with a digital mixing console which converts all the analog signals from the stage into digital signals. Comparable with the audio-files on your computer. TheWynner is talking about clipping on the output bus. This means, that the signals coming from the stage are fine. But when combined inside the console, they are too loud. They are over the limit of the highest digital loudness which leads to unpleasant noise. Each signal can be controlled in volume individually via a gain-setting, and all signal's gain-settings combined are called the gain stage. The signal-to-noise ratio is also a digital term. Here noise means the lowest volume you can possibly reproduce in a digital context. Good signal-to-noise ratio then means that your signals are loud enough but not clipping. Headroom means the amount of decibels between your signal and when it would start clipping.
If need be we can throw a limiter after the EQ and sidechained multiband compressor to clean that up.
A limiter is a signal processor which ensures that your signal is not clipping. Even though it might prevent clipping, it also strongly alters your signal if it would be clipping. Generally, a limiter is only used for safety. The EQ means an Equalizer. A more sophisticated version of what you might know by the terms Bass and Treble. A compressor is a signal processor that makes quiet signals louder and loud signals quieter. Everyone uses compression. It's the reason you can hear someone whisper and someone shout on television without having to adjust the volume. A multi band compressor compresses different frequency ranges differently. You can also have a compressor react on not the signal that is flowing though it but on a different signal. The first over-the-top use of side-chaining a compressor that was widely noticed was Eric Prydz - Call On Me. He used the kick drum as a side chain for the compressor on the synthesizer.
Speaking of EQ the overheads are getting some nasty 250s so you should probably just notch that out or just highpass it.
The "overheads" means the microphones positioned over the drums (normally 2 of them). They are mostly there for picking up the cymbals of the drum set. "nasty 250s" means there is a sound coming from the overheads that is too dominant in the range of 250Hz. That could be the tom-toms of the drum set or even the guitar-player's guitar being recorded by the drummer's overheads. "notch" and "highpass" are two special filter-settings which you can apply in the EQ-stage.
Lastly, the u89 is a condenser so make sure phantom power is engaged but don't engage it on the R122 because then you'll shred the ribbon.
The u98 is a condenser microphone by Neumann. It is most likely the singers microphone. Phantom power is an electrical current needed for condenser microphones because their diaphragm acts as a plate with a capacitor (so there needs to be current running through the microphone cable for the mic to make sound). The u98 is a microphone that needs phantom power. The other microphone, the R122 does not. And it is important, that it does not receive any because it is a ribbon microphone which would easily be damaged by an external current running through it.