“Degree” here just means scale degree — the same numbering from the first page of the lesson (1 = C, 2 = D, 3 = E… in the key of C). So “the V chord of that degree” means: pick any one of the 7 numbers, temporarily pretend that note is the “1” of its own key, and build the V chord as if it were.
Worked example, still in C major:
Say he wants extra pull toward degree 5 (G) before landing on it.
- Pretend G is temporarily “home” (its own key of G major)
- In the key of G, the V chord is D major (G’s own 5th note is D, and D major is built on it)
- Borrow that D major chord and drop it into the C major song, right before the G chord
So the progression becomes: C → D → G instead of the plain diatonic C → Am → G. That borrowed D major is labeled V/V (“five of five”) — and notice D major isn’t in his C major table at all (the diatonic chord on degree 2 is D minor). That’s exactly the kind of “chord that doesn’t match the chart” from Section 5b.
The shorthand he’ll see in real chord charts: V/ii, V/IV, V/vi, etc. — always read as “the V chord of that particular degree,” built as if that degree were its own temporary key, then borrowed back in.