Good jazz takes a lot of communication

Good jazz takes a lot of communication, now I know. I don’t speak any languages other than English. Despite three years of German classes in high school, I can’t speak German. Despite spending time in Brazil and Mexico, I can’t speak Portuguese or Spanish.
And I just found out I can’t speak Jazz either.
I was lucky enough to be invited to sit in on a rehearsal with Shola, his pianist Philip, and drummer Yakou.
The music was fantastic, but what really fascinated me was the conversations the three musicians had with each other.
“So that’s 6, 4, 3, 1?” Shola asked. “No, it’s 6, 4, 2, 1,” Philip replied as he played it on the piano.
Starting another song, Shola said, “On this we’ll do Intro, A, B, C, B, Intro”
(*) The conversations above are my best recollections of what was said, but they might not be entirely accurate. I’d have about as much luck remembering a conversation in Portuguese.
Good jazz takes a lot of communication. As best I can tell, the only “sheet music” a jazz musician needs to play an entire song consists only of the names of a few chords written out on one line of text, something like this:
EM7   Bm7   E7   AM7   D7   EM7   C#m7
For multiple people to play in sync from just that line of chords, takes some serious jazz communication skills. 
As far as those conversations I heard, Shola explained that the numeric conversation related to the chords Philip was playing on that song. Referring to the chords as numbers lets a jazz musician play the proper chords, no matter what key the group ends up playing in. This is really handy for the improvisation that is a natural part of jazz music.
The A-B sequence of letters referred to the sections of the song, with each section containing a prescribed number of bars and phrases that define the meter of the song. The meter is, ummm…
Well, I’ve reached the end of my jazz linguistic abilities.
The absolute best way to understand what Shola, Philip, and Yakou were saying – is to listen to their music.
You’ll have no problem translating that.