He is talking about "zooming" the waveform scale up. In otherwords, not making the track taller or focusing in on a frame to magnify the view of the timeline, nor changing the gain on the clip to make the waveform larger. He means zoom the scale up, so that the height of the waveforms are magnified to reveal a more sensitive readout of quieter audio.
It's not a FCP option, so I can understand why people do not understand the question, but it is a great feature of other software.